Chapter 21 MySQL NDB Cluster 7.5 and NDB Cluster 7.6

ndbinfo Enhancements.  A number of changes are made in the ndbinfo database, chief of which is that it now provides detailed information about NDB Cluster node configuration parameters.

ndbinfo增强。在ndbinfo数据库中进行了许多更改，主要是现在它提供了有关ndb集群节点配置参数的详细信息。

The config_params table has been made read-only, and has been enhanced with additional columns providing information about each configuration parameter, including the parameter's type, default value, maximum and minimum values (where applicable), a brief description of the parameter, and whether the parameter is required. This table also provides each parameter with a unique param_number.

CopyToPARAMS表已被只读，并且已经增强了附加列，这些列提供有关每个配置参数的信息，包括参数的类型、默认值、最大值和最小值（在适用的情况下）、参数的简要描述以及参数是否需要。此表还为每个参数提供唯一的参数编号。

A row in the config_values table shows the current value of a given parameter on the node having a specified ID. The parameter is identified by the value of the config_param column, which maps to the config_params table's param_number.

配置值表中的一行显示具有指定ID的节点上给定参数的当前值。该参数由配置参数列的值标识，该列映射到配置参数表的参数号。

Using this relationship you can write a join on these two tables to obtain the default, maximum, minimum, and current values for one or more NDB Cluster configuration parameters by name. An example SQL statement using such a join is shown here:

使用此关系，您可以在这两个表上写入一个连接，以获得一个或多个NDB集群配置参数的默认值、最大值、最小值和当前值。下面显示了使用这种联接的示例SQL语句：

SELECT  p.param_name AS Name,
        v.node_id AS Node,
        p.param_type AS Type,
        p.param_default AS 'Default',
        p.param_min AS Minimum,
        p.param_max AS Maximum,
        CASE p.param_mandatory WHEN 1 THEN 'Y' ELSE 'N' END AS 'Required',
        v.config_value AS Current
FROM    config_params p
JOIN    config_values v
ON      p.param_number = v.config_param
WHERE   p. param_name IN ('NodeId', 'HostName','DataMemory', 'IndexMemory');

For more information about these changes, see Section 21.5.10.8, “The ndbinfo config_params Table”. See Section 21.5.10.9, “The ndbinfo config_values Table”, for further information and examples.

有关这些更改的更多信息，请参阅21.5.10.8节，“ndbinfo config_params表”。有关更多信息和示例，请参阅第21.5.10.9节“ndbinfo配置值表”。

In addition, the ndbinfo database no longer depends on the MyISAM storage engine. All ndbinfo tables and views now use NDB (shown as NDBINFO).

此外，ndbinfo数据库不再依赖myisam存储引擎。所有ndbinfo表和视图现在都使用ndb（显示为ndbinfo）。

Several new ndbinfo tables were introduced in NDB 7.5.4. These tables are listed here, with brief descriptions:

在ndb 7.5.4中引入了几个新的ndbinfo表。下面列出这些表格，并简要说明：

See the descriptions of the individual tables for more information.

有关详细信息，请参见各个表的说明。

Default row and column format changes.  Starting with NDB 7.5.1, the default value for both the ROW_FORMAT option and the COLUMN_FORMAT option for CREATE TABLE can be set to DYNAMIC rather than FIXED, using a new MySQL server variable ndb_default_column_format is added as part of this change; set this to FIXED or DYNAMIC (or start mysqld with the equivalent option --ndb-default-column-format=FIXED) to force this value to be used for COLUMN_FORMAT and ROW_FORMAT. Prior to NDB 7.5.4, the default for this variable was DYNAMIC; in this and later versions, the default is FIXED, which provides backwards compatibility with prior releases (Bug #24487363).

默认行和列格式更改。从ndb 7.5.1开始，row_format选项和column_format选项的默认值都可以设置为dynamic而不是fixed，使用新的mysql服务器变量ndb_default_column_format作为此更改的一部分被添加；将其设置为fixed或dynamic（或使用等效选项启动mysqld--ndb default column format=fixed），以强制将此值用于column_format和row_format。在ndb 7.5.4之前，这个变量的默认值是动态的；在这个和更高版本中，默认值是固定的，它提供了与以前版本的向后兼容性（bug 24487363）。

The row format and column format used by existing table columns are unaffected by this change. New columns added to such tables use the new defaults for these (possibly overridden by ndb_default_column_format), and existing columns are changed to use these as well, provided that the ALTER TABLE statement performing this operation specifies ALGORITHM=COPY.

由现有表列使用的行格式和列格式不受此更改的影响。添加到这些表中的新列使用这些新的默认值（可能被NdByDebug ToLnnx格式重写），并且现有的列也被更改为使用这些，只要执行此操作的ALTALTABLE语句指定“算法=复制”。

ndb_binlog_index no longer dependent on MyISAM.  As of NDB 7.5.2, the ndb_binlog_index table employed in NDB Cluster Replication now uses the InnoDB storage engine instead of MyISAM. When upgrading, you can run mysql_upgrade with --force --upgrade-system-tables to cause it to execute ALTER TABLE ... ENGINE=INNODB on this table. Use of MyISAM for this table remains supported for backward compatibility.

ndb_binlog_索引不再依赖myisam。从ndb 7.5.2开始，ndb集群复制中使用的ndb-binlog-u索引表现在使用的是innodb存储引擎，而不是myisam。升级时，可以使用--force--upgrade系统表运行mysql_upgrade，使其执行alter table…engine=innodb在这个表上。为了向后兼容，仍然支持对此表使用myisam。

A benefit of this change is that it makes it possible to depend on transactional behavior and lock-free reads for this table, which can help alleviate concurrency issues during purge operations and log rotation, and improve the availability of this table.

此更改的一个好处是，它使依赖此表的事务行为和无锁读取成为可能，这有助于缓解清除操作和日志循环期间的并发问题，并提高此表的可用性。

ALTER TABLE changes.  NDB Cluster formerly supported an alternative syntax for online ALTER TABLE. This is no longer supported in NDB Cluster 7.5, which makes exclusive use of ALGORITHM = DEFAULT|COPY|INPLACE for table DDL, as in the standard MySQL Server.

更改表更改。ndb集群以前支持在线alter table的替代语法。ndb cluster 7.5不再支持这一点，因为它只对表ddl使用algorithm=default copy inplace，就像在标准mysql服务器中一样。

Another change affecting the use of this statement is that ALTER TABLE ... ALGORITHM=INPLACE RENAME may now contain DDL operations in addition to the renaming.

影响此语句使用的另一个更改是alter table…algorithm=inplace rename现在除了重命名之外，还可以包含ddl操作。

ExecuteOnComputer parameter deprecated.  The ExecuteOnComputer configuration parameter for management nodes, data nodes, and API nodes has been deprecated and is now subject to removal in a future release of NDB Cluster. You should use the equivalent HostName parameter for all three types of nodes.

ExecuteOnComputer参数已弃用。管理节点、数据节点和api节点的executeoncomputer配置参数已被弃用，现在可以在ndb集群的未来版本中删除。您应该对所有三种类型的节点使用等效的hostname参数。

records-per-key optimization.  The NDB handler now uses the records-per-key interface for index statistics implemented for the optimizer in MySQL 5.7.5. Some of the benefits from this change include those listed here:

按密钥优化记录。ndb处理程序现在使用records per key接口来统计mysql 5.7.5中优化器实现的索引。此更改带来的一些好处包括：

Connection pool node IDs.  NDB 7.5.0 adds the mysqld --ndb-cluster-connection-pool-nodeids option, which allows a set of node IDs to be set for the connection pool. This setting overrides --ndb-nodeid, which means that it also overrides both the --ndb-connectstring option and the NDB_CONNECTSTRING environment variable.

连接池节点ID。ndb 7.5.0添加了mysqld--ndb cluster connection pool node ids选项，该选项允许为连接池设置一组节点id。此设置重写--ndb nodeid，这意味着它还重写--ndb connectstring选项和ndb_connectstring环境变量。

create_old_temporals removed.  The create_old_temporals system variable was deprecated in NDB Cluster 7.4, and has now been removed.

创建已删除的旧临时项。在ndb cluster 7.4中，create_old_temporals系统变量已被弃用，现在已被删除。

ndb_mgm Client PROMPT command.  NDB Cluster 7.5 adds a new command for setting the client's command-line prompt. The following example illustrates the use of the PROMPT command:

ndb_mgm client prompt命令。ndb cluster 7.5添加了一个新命令，用于设置客户端的命令行提示符。下面的示例演示了prompt命令的使用：

ndb_mgm> PROMPT mgm#1:
mgm#1: SHOW
Cluster Configuration
---------------------
[ndbd(NDB)]     4 node(s)
id=5    @10.100.1.1  (mysql-5.7.28-ndb-7.5.16, Nodegroup: 0, *)
id=6    @10.100.1.3  (mysql-5.7.28-ndb-7.5.16, Nodegroup: 0)
id=7    @10.100.1.9  (mysql-5.7.28-ndb-7.5.16, Nodegroup: 1)
id=8    @10.100.1.11  (mysql-5.7.28-ndb-7.5.16, Nodegroup: 1)

[ndb_mgmd(MGM)] 1 node(s)
id=50   @10.100.1.8  (mysql-5.7.28-ndb-7.5.16)

[mysqld(API)]   2 node(s)
id=100  @10.100.1.8  (5.7.28-ndb-7.5.16)
id=101  @10.100.1.10  (5.7.28-ndb-7.5.16)

mgm#1: PROMPT
ndb_mgm> EXIT
jon@valhaj:/usr/local/mysql/bin>

For additional information and examples, see Section 21.5.2, “Commands in the NDB Cluster Management Client”.

有关更多信息和示例，请参阅21.5.2节，“ndb群集管理客户端中的命令”。

Increased FIXED column storage per fragment.  NDB Cluster 7.5 and later supports a maximum of 128 TB per fragment of data in FIXED columns. In NDB Cluster 7.4 and earlier, this was 16 GB per fragment.

增加了每个片段的固定列存储。NDB集群7.5和以后支持在固定列中每个数据片段最多128个TB。在ndb集群7.4及更早版本中，每个片段的容量为16gb。

Deprecated parameters removed.  The following NDB Cluster data node configuration parameters were deprecated in previous releases of NDB Cluster, and were removed in NDB 7.5.0:

已删除不推荐使用的参数。以下ndb群集数据节点配置参数在ndb群集的早期版本中已弃用，并在ndb 7.5.0中删除：

The archaic and unused (and for this reason also previously undocumented) ByteOrder computer configuration parameter was also removed in NDB 7.5.0.

在ndb 7.5.0中还删除了过时的和未使用的字节顺序计算机配置参数（由于这个原因以前也没有记录）。

The parameters just described are not supported in NDB 7.5. Attempting to use any of these parameters in an NDB Cluster configuration file now results in an error.

ndb 7.5不支持刚才描述的参数。尝试在ndb群集配置文件中使用这些参数会导致错误。

DBTC scan enhancements.  Scans have been improved by reducing the number of signals used for communication between the DBTC and DBDIH kernel blocks in NDB, enabling higher scalability of data nodes when used for scan operations by decreasing the use of CPU resources for scan operations, in some cases by an estimated five percent.

DBTC扫描增强功能。通过减少用于ndb中dbtc和dbdih内核块之间通信的信号的数量，扫描得到了改进，当用于扫描操作时，通过减少用于扫描操作的cpu资源的使用（在某些情况下估计为5%），使数据节点具有更高的可伸缩性。

Also as result of these changes response times should be greatly improved, which could help prevent issues with overload of the main threads. In addition, scans made in the BACKUP kernel block have also been improved and made more efficient than in previous releases.

此外，由于这些更改，响应时间应该大大提高，这有助于防止主线程过载的问题。此外，在备份内核块中进行的扫描也得到了改进，比以前的版本更加高效。

JSON column support.  NDB 7.5.2 and later supports the JSON column type for NDB tables and the JSON functions found in the MySQL Server, subject to the limitation that an NDB table can have at most 3 JSON columns.

JSON列支持。ndb 7.5.2及更高版本支持ndb表的json列类型和mysql服务器中的json函数，但ndb表最多只能有3个json列。

Read from any replica; specify number of hashmap partition fragments.  Previously, all reads were directed towards the primary replica except for simple reads. (A simple read is a read that locks the row while reading it.) Beginning with NDB 7.5.2, it is possible to enable reads from any replica. This is disabled by default but can be enabled for a given SQL node using the ndb_read_backup system variable added in this release.

从任何副本读取；指定哈希映射分区片段的数量。以前，除了简单读取之外，所有读取都定向到主副本。（简单读取是在读取行时锁定行的读取。）从ndb 7.5.2开始，可以启用对任何副本的读取。这在默认情况下是禁用的，但可以使用此版本中添加的ndb_read_backup系统变量为给定的sql节点启用。

Previously, it was possible to define tables with only one type of partition mapping, with one primary partition on each LDM in each node, but in NDB 7.5.2 it becomes possible to be more flexible about the assignment of partitions by setting a partition balance (fragment count type). Possible balance schemes are one per node, one per node group, one per LDM per node, and one per LDM per node group.

以前，可以定义只有一种类型的分区映射表，每个节点上的每个LDM都有一个主分区，但是在NDB 7.5.2中，通过设置分区平衡（片段计数类型），可以更灵活地分配分区。可能的平衡方案是每个节点一个，每个节点组一个，每个ldm每个节点一个，每个ldm每个节点组一个。

This setting can be controlled for individual tables by means of a PARTITION_BALANCE option (renamed from FRAGMENT_COUNT_TYPE in NDB 7.5.4) embedded in NDB_TABLE comments in CREATE TABLE or ALTER TABLE statements. Settings for table-level READ_BACKUP are also supported using this syntax. For more information and examples, see Section 13.1.18.10, “Setting NDB_TABLE Options”.

此设置可以通过分区的Type平衡选项（从NDB 7.5.4中的FractMyCurtType类型重命名）在单个表中被控制，在NETBYTABLE表中嵌入在创建表或ALTALTABLE语句中。使用此语法还支持表级读取备份的设置。有关更多信息和示例，请参阅第13.1.18.10节“设置ndb_表选项”。

In NDB API applications, a table's partition balance can also be get and set using methods supplied for this purpose; see Table::getPartitionBalance(), and Table::setPartitionBalance(), as well as Object::PartitionBalance, for more information about these.

在ndb api应用程序中，还可以使用为此目的提供的方法来获取和设置表的分区平衡；有关这些方法的详细信息，请参阅table：：get partition balance（）、table：：setpartitionbalance（）和object：：partitionbalance。

As part of this work, NDB 7.5.2 also introduces the ndb_data_node_neighbour system variable. This is intended for use, in transaction hinting, to provide a “nearby” data node to this SQL node.

作为这项工作的一部分，ndb 7.5.2还引入了ndb_data_node_neighbor系统变量。这是为了在事务提示中向这个sql节点提供一个“附近”的数据节点。

In addition, when restoring table schemas, ndb_restore --restore-meta now uses the target cluster's default partitioning, rather than using the same number of partitions as the original cluster from which the backup was taken. See Section 21.4.24.1.2, “Restoring to More Nodes Than the Original”, for more information and an example.

此外，在还原表模式时，ndb_restore--restore meta现在使用目标集群的默认分区，而不是使用与从中进行备份的原始集群相同数量的分区。有关更多信息和示例，请参阅第21.4.24.1.2节“还原到比原始节点更多的节点”。

NDB 7.5.3 adds a further enhancement to READ_BACKUP: In this and later versions, it is possible to set READ_BACKUP for a given table online as part of ALTER TABLE ... ALGORITHM=INPLACE ....

ndb 7.5.3增加了对read_backup的进一步增强：在这个和更高版本中，可以将给定表的read_backup设置为alter table的一部分……算法=就地….

ThreadConfig improvements.  A number of enhancements and feature additions are implemented in NDB 7.5.2 for the ThreadConfig multithreaded data node (ndbmtd) configuration parameter, including support for an increased number of platforms. These changes are described in the next few paragraphs.

threadconfig改进。在ndb 7.5.2中，为threadconfig多线程数据节点（ndbmtd）配置参数实现了许多增强和特性添加，包括对更多平台的支持。下面几段将介绍这些变化。

Non-exclusive CPU locking is now supported on FreeBSD and Windows, using cpubind and cpuset. Exclusive CPU locking is now supported on Solaris (only) using the cpubind_exclusive and cpuset_exclusive parameters which are introduced in this release.

使用cpubind和cpuset，freebsd和windows现在支持非独占cpu锁定。现在，在solaris上（仅）使用本版本中引入的cpubind_exclusive和cpuset_exclusive参数支持独占cpu锁定。

Thread prioritzation is now available, controlled by the new thread_prio parameter. thread_prio is supported on Linux, FreeBSD, Windows, and Solaris, and varies somewhat by platform. For more information, see the description of ThreadConfig.

线程优先级现在可用，由新的thread prio参数控制。thread_prio在linux、freebsd、windows和solaris上受支持，并且随平台的不同而有所不同。有关详细信息，请参阅threadconfig的说明。

The realtime parameter is now supported on Windows platforms.

windows平台现在支持realtime参数。

Partitions larger than 16 GB.  Due to an improvement in the hash index implementation used by NDB Cluster data nodes, partitions of NDB tables may now contain more than 16 GB of data for fixed columns, and the maximum partition size for fixed columns is now raised to 128 TB. The previous limitation was due to the fact that the DBACC block in the NDB kernel used only 32-bit references to the fixed-size part of a row in the DBTUP block, although 45-bit references to this data are used in DBTUP itself and elsewhere in the kernel outside DBACC; all such references in to the data handled in the DBACC block now use 45 bits instead.

大于16GB的分区。由于NDB集群数据节点使用的散列索引实现的改进，NDB表的分区现在可以包含超过16 GB的固定列数据，并且固定列的最大分区大小现在提高到128 TB。先前的限制是由于ndb内核中的dbacc块仅使用32位对dbtup块中行的固定大小部分的引用，尽管dbtup本身和dbacc之外的内核中的其他地方使用了对该数据的45位引用；现在对dbacc块中处理的数据的所有此类引用都使用45位。相反。

Print SQL statements from ndb_restore.  NDB 7.5.4 adds the --print-sql-log option for the ndb_restore utility provided with the NDB Cluster distribution. This option enables SQL logging to stdout. Important: Every table to be restored using this option must have an explicitly defined primary key.

从ndb_restore打印sql语句。ndb 7.5.4为ndb集群分发提供的ndb_restore实用程序添加了--print sql log选项。此选项允许将SQL日志记录到stdout。重要提示：使用此选项还原的每个表都必须具有显式定义的主键。

See Section 21.4.24, “ndb_restore — Restore an NDB Cluster Backup”, for more information.

有关详细信息，请参阅21.4.24节“ndb_restore-restore an ndb cluster backup”。

Organization of RPM packages.  Beginning with NDB 7.5.4, the naming and organization of RPM packages provided for NDB Cluster align more closely with those released for the MySQL server. The names of all NDB Cluster RPMs are now prefixed with mysql-cluster. Data nodes are now installed using the data-node package; management nodes are now installed from the management-server package; and SQL nodes require the server and common packages. MySQL and NDB client programs, including the mysql client and the ndb_mgm management client, are now included in the client RPM.

RPM包的组织。从ndb 7.5.4开始，为ndb集群提供的rpm包的命名和组织与为mysql服务器发布的rpm包更加紧密地结合在一起。所有ndb集群rpm的名称现在都以mysql cluster作为前缀。数据节点现在使用数据节点包安装；管理节点现在从管理服务器包安装；sql节点需要服务器和公共包。mysql和ndb客户机程序，包括mysql客户机和ndb-mgm管理客户机，现在包含在客户机rpm中。

For a detailed listing of NDB Cluster RPMs and other information, see Section 21.2.3.2, “Installing NDB Cluster from RPM”.

有关ndb集群rpm的详细列表和其他信息，请参阅第21.2.3.2节“从rpm安装ndb集群”。

ndbinfo processes and config_nodes tables.  NDB 7.5.7 adds two tables to the ndbinfo information database to provide information about cluster nodes; these tables are listed here:

ndbinfo进程和配置节点表。ndb 7.5.7将两个表添加到ndbinfo信息数据库中，以提供有关群集节点的信息；下面列出了这些表：

System name.  The system name of an NDB cluster can be used to identify a specific cluster. Beginning with NDB 7.5.7, the MySQL Server shows this name as the value of the Ndb_system_name status variable; NDB API applications can use the Ndb_cluster_connection::get_system_name() method which is added in the same release.

系统名称。ndb集群的系统名称可用于标识特定集群。从ndb 7.5.7开始，mysql服务器将此名称显示为ndb_system_name状态变量的值；ndb api应用程序可以使用在同一版本中添加的ndb_cluster_connection：：get_system_name（）方法。

A system name based on the time the management server was started is generated automatically; you can override this value by adding a [system] section to the cluster's configuration file and setting the Name parameter to a value of your choice in this section, prior to starting the management server.

系统将根据管理服务器启动的时间自动生成系统名称；在启动管理服务器之前，可以通过向群集的配置文件中添加一个[system]节并将name参数设置为您在此节中选择的值来覆盖此值。

ndb_restore options.  Beginning with NDB 7.5.13, the --nodeid and --backupid options are both required when invoking ndb_restore.

ndb_还原选项。从ndb 7.5.13开始，--nodeid和--backupid选项在调用ndb_restore时都是必需的。

New Disk Data table file format.  A new file format was introduced in NDB 7.6.2 for NDB Disk Data tables, which makes it possible for each Disk Data table to be uniquely identified without reusing any table IDs. The format was improved further in NDB 7.6.4. This should help resolve issues with page and extent handling that were visible to the user as problems with rapid creating and dropping of Disk Data tables, and for which the old format did not provide a ready means to fix.

新的磁盘数据表文件格式。在ndb 7.6.2中为ndb磁盘数据表引入了一种新的文件格式，使得每个磁盘数据表都可以唯一标识，而不必重用任何表id。在ndb 7.6.4中进一步改进了格式。这将有助于解决在快速创建和删除磁盘数据表时对用户可见的页面和数据块处理问题，而对于这些问题，旧格式没有提供现成的解决方法。

The new format is now used whenever new undo log file groups and tablespace data files are created. Files relating to existing Disk Data tables continue to use the old format until their tablespaces and undo log file groups are re-created.

新格式现在在创建新的撤消日志文件组和表空间数据文件时使用。与现有磁盘数据表相关的文件继续使用旧格式，直到重新创建表空间和撤销日志文件组为止。

To avoid problems relating to the changes in format, you should re-create any existing tablespaces and undo log file groups when upgrading to NDB 7.6.2 or NDB 7.6.4. You can do this by performing an initial restart of each data node (that is, using the --initial option) as part of the upgrade process. You can expect this step to be made mandatory as part of upgrading from NDB 7.5 or an earlier release series to NDB 7.6 or later.

为了避免与格式更改有关的问题，在升级到NDB 7.62或NDB 7.64.4时，应重新创建任何现有表空间和撤销日志文件组。作为升级过程的一部分，您可以执行每个数据节点的初始重新启动（即使用--initial选项）。作为从ndb 7.5或更早版本系列升级到ndb7.6或更高版本系列的一部分，您可以预期此步骤是必需的。

If you are using Disk Data tables, a downgrade from any NDB 7.6 release—without regard to release status—to any NDB 7.5 or earlier release requires that you restart all data nodes with --initial as part of the downgrade process. This is because NDB 7.5 and earlier release series are not able to read the new Disk Data file format.

如果您使用的是磁盘数据表，从任何ndb 7.6版本（不考虑版本状态）降级到任何ndb7.5或更早版本需要重新启动所有数据节点，并在降级过程中使用--initial。这是因为ndb 7.5和早期版本系列无法读取新的磁盘数据文件格式。

For more information, see Section 21.2.9, “Upgrading and Downgrading NDB Cluster”.

有关更多信息，请参阅第21.2.9节“升级和降级ndb集群”。

Data memory pooling and dynamic index memory.  Memory required for indexes on NDB table columns is now allocated dynamically from that allocated for DataMemory. For this reason, the IndexMemory configuration parameter is now deprecated, and subject to removal in a future release series.

数据内存池和动态索引内存。ndb表列上的索引所需的内存现在是从为datamemory分配的内存中动态分配的。因此，indexMemory配置参数现在已被弃用，并将在以后的发行版系列中删除。

The pooling together of index memory with data memory simplifies the configuration of NDB; a further benefit of these changes is that scaling up by increasing the number of LDM threads is no longer limited by having set an insufficiently large value for IndexMemory.This is because index memory is no longer a static quantity which is allocated only once (when the cluster starts), but can now be allocated and deallocated as required. Previously, it was sometimes the case that increasing the number of LDM threads could lead to index memory exhaustion while large amounts of DataMemory remained available.

索引内存和数据内存的合用简化了ndb的配置；这些更改的另一个好处是，通过增加ldm线程的数量来扩展ndb不再受到为index memory设置一个不够大的值的限制。这是因为索引内存不再是只分配给ndb的静态数量。一次（当集群启动时），但现在可以根据需要分配和解除分配。以前，有时增加ldm线程的数量会导致索引内存耗尽，而大量数据内存仍然可用。

As part of this work, a number of instances of DataMemory usage not directly related to storage of table data now use transaction memory instead.

作为这项工作的一部分，许多与表数据的存储没有直接关系的数据内存使用实例现在使用事务内存。

For this reason, it may be necessary on some systems to increase SharedGlobalMemory to allow transaction memory to increase when needed, such as when using NDB Cluster Replication, which requires a great deal of buffering on the data nodes. On systems performing initial bulk loads of data, it may be necessary to break up very large transactions into smaller parts.

因此，在某些系统上可能需要增加sharedglobalmemory，以允许在需要时增加事务内存，例如在使用ndb集群复制时，这需要在数据节点上进行大量缓冲。在执行初始大容量数据加载的系统上，可能需要将非常大的事务分解为较小的部分。

In addition, data nodes now generate MemoryUsage events (see Section 21.5.6.2, “NDB Cluster Log Events”) and write appropriate messages in the cluster log when resource usage reaches 99%, as well as when it reaches 80%, 90%, or 100%, as before.

此外，数据节点现在生成memoryUsage事件（请参阅第21.5.6.2节“ndb集群日志事件”），并在资源使用率达到99%以及达到80%、90%或100%时在集群日志中写入适当的消息。

Other related changes are listed here:

其他相关变更如下：

ndbinfo processes and config_nodes tables.  NDB 7.6.2 adds two tables to the ndbinfo information database to provide information about cluster nodes; these tables are listed here:

ndbinfo进程和配置节点表。ndb 7.6.2在ndbinfo信息数据库中添加了两个表，以提供有关群集节点的信息；这些表如下所示：

System name.  The system name of an NDB cluster can be used to identify a specific cluster. Beginning with NDB 7.6.2, the MySQL Server shows this name as the value of the Ndb_system_name status variable; NDB API applications can use the Ndb_cluster_connection::get_system_name() method which is added in the same release.

系统名称。ndb集群的系统名称可用于标识特定集群。从ndb 7.6.2开始，mysql服务器将此名称显示为ndb_system_name状态变量的值；ndb api应用程序可以使用在同一版本中添加的ndb_cluster_connection：：get_system_name（）方法。

A system name based on the time the management server was started is generated automatically>; you can override this value by adding a [system] section to the cluster's configuration file and setting the Name parameter to a value of your choice in this section, prior to starting the management server.

基于管理服务器启动时间的系统名称将自动生成>；您可以在启动管理服务器之前，通过在群集的配置文件中添加[system]节并将name参数设置为您在此节中选择的值来覆盖此值。

Improved GUI installer.  The NDB Cluster Auto-Installer has been enhanced in a number of respects, as described in the following list:

改进的gui安装程序。ndb集群自动安装程序在许多方面得到了增强，如下表所示：

For more details and usage information, see Section 21.2.2, “The NDB Cluster Auto-Installer (NDB 7.6)”.

有关更多详细信息和用法信息，请参阅21.2.2节，“ndb群集自动安装程序（ndb 7.6）”。

ndb_import CSV import tool.  ndb_import, added in NDB Cluster 7.6.2, loads CSV-formatted data directly into an NDB table using the NDB API (a MySQL server is needed only to create the table and database in which it is located). ndb_import can be regarded as an analog of mysqlimport or the LOAD DATA INFILE SQL statement, and supports many of the same or similar options for formatting of the data.

ndb_导入csv导入工具。添加在ndb cluster 7.6.2中的ndb_import使用ndb api将csv格式的数据直接加载到ndb表中（只需要一个mysql服务器来创建它所在的表和数据库）。ndb_import可以看作是mysqlimport或load data infile sql语句的模拟，并且支持许多相同或类似的数据格式化选项。

Assuming that the database and target NDB table exist, ndb_import needs only a connection to the cluster's management server (ndb_mgmd) to perform the importation; for this reason, there must be an [api] slot available to the tool in the cluster's config.ini file purpose.

假设数据库和目标NDB表存在，NdBy导入只需要连接到集群管理服务器（NdByMGMD）来执行导入；为此，必须有一个[API]槽可用在集群的CONTION.IN文件中的工具中。

See Section 21.4.14, “ndb_import — Import CSV Data Into NDB”, for more information.

有关详细信息，请参阅第21.4.14节“ndb_导入-将csv数据导入ndb”。

ndb_top monitoring tool.  Added the ndb_top utility, which shows CPU load and usage information for an NDB data node in real time. This information can be displayed in text format, as an ASCII graph, or both. The graph can be shown in color, or using grayscale.

ndb_顶部监控工具。添加了ndb_top实用程序，它实时显示ndb数据节点的cpu负载和使用信息。此信息可以文本格式、ascii图形或两者都显示。图形可以用颜色显示，也可以用灰度显示。

ndb_top connects to an NDB Cluster SQL node (that is, a MySQL Server). For this reason, the program must be able to connect as a MySQL user having the SELECT privilege on tables in the ndbinfo database.

ndb_u top连接到ndb集群sql节点（即mysql服务器）。因此，该程序必须能够以对ndbinfo数据库中的表具有select权限的mysql用户身份进行连接。

ndb_top is available for Linux, Solaris, and Mac OS X platforms beginning with NDB 7.6.3. It is not currently available for Windows platforms.

ndb_u top可用于从ndb 7.6.3开始的linux、solaris和mac os x平台。它目前不适用于windows平台。

For more information, see Section 21.4.30, “ndb_top — View CPU usage information for NDB threads”.

有关更多信息，请参阅21.4.30节，“ndb_top-查看ndb线程的cpu使用信息”。

Code cleanup.  A significant number of debugging statements and printouts not necessary for normal operations have been moved into code used only when testing or debugging NDB, or dispensed with altogether. This removal of overhead should result in a noticeable improvement in the performance of LDM and TC threads on the order of 10% in many cases.

代码清理。大量正常操作不需要的调试语句和打印输出被转移到只在测试或调试ndb时使用的代码中，或者完全不需要。在许多情况下，这种开销的消除将显著提高ldm和tc线程的性能，大约为10%。

LDM thread and LCP improvements.  Previously, when a local data management thread experienced I/O lag, it wrote to local checkpoints more slowly. This could happen, for example, during a disk overload condition. Problems could occur because other LDM threads did not always observe this state, or do likewise. NDB now tracks I/O lag mode globally, so that this state is reported as soon as at least one thread is writing in I/O lag mode; it then makes sure that the reduced write speed for this LCP is enforced for all LDM threads for the duration of the slowdown condition. Because the reduction in write speed is now observed by other LDM instances, overall capacity is increased; this enables the disk overload (or other condition inducing I/O lag) to be overcome more quickly in such cases than it was previously.

LDM线程和LCP改进。以前，当本地数据管理线程遇到I/O延迟时，它向本地检查点的写入速度会慢一些。例如，在磁盘过载情况下，可能会发生这种情况。可能会出现问题，因为其他ldm线程并不总是观察到这种状态，或者执行类似的操作。ndb现在全局跟踪i/o延迟模式，以便在至少一个线程以i/o延迟模式写入时立即报告此状态；然后，它确保在减速条件期间对所有ldm线程强制执行此lcp的降低写入速度。由于其他ldm实例现在可以观察到写入速度的降低，因此总容量增加；这使得在这种情况下，比以前更快地克服磁盘过载（或导致i/o延迟的其他条件）。

NDB error identification.  Error messages and information can be obtained using the mysql client in NDB 7.6.4 and later from a new error_messages table in the ndbinfo information database. In addition, the 7.6.4 release introduces a command-line client ndb_perror for obtaining information from NDB error codes; this replaces using perror with --ndb, which is now deprecated and subject to removal in a future release.

ndb错误识别。可以使用ndb 7.6.4中的mysql客户端以及更高版本从ndbinfo信息数据库中的一个新的错误信息表中获取错误信息和信息。此外，7.6.4版本引入了一个命令行客户机ndb_perror，用于从ndb错误代码获取信息；这将perror替换为--ndb，后者现在已被弃用，在将来的版本中将被删除。

For more information, see Section 21.5.10.21, “The ndbinfo error_messages Table”, and Section 21.4.17, “ndb_perror — Obtain NDB Error Message Information”.

有关详细信息，请参阅第21.5.10.21节“ndbinfo error_messages表”和第21.4.17节“ndb_perror-获取ndb错误消息信息”。

SPJ improvements.  When executing a scan as a pushed join (that is, the root of the query is a scan), the DBTC block sends an SPJ request to a DBSPJ instance on the same node as the fragment to be scanned. Formerly, one such request was sent for each of the node's fragments. As the number of DBTC and DBSPJ instances is normally set less than the number of LDM instances, this means that all SPJ instances were involved in the execution of a single query, and, in fact, some SPJ instances could (and did) receive multiple requests from the same query. In NDB 7.6.4, it becomes possible for a single SPJ request to handle a set of root fragments to be scanned, so that only a single SPJ request (SCAN_FRAGREQ) needs to be sent to any given SPJ instance (DBSPJ block) on each node.

SPJ改进。当作为一个推式连接执行扫描（即，查询的根是一个扫描）时，dbtc块将spj请求发送到与要扫描的片段位于同一节点上的dbspj实例。以前，为每个节点的片段发送一个这样的请求。由于dbtc和dbspj实例的数量通常设置为小于ldm实例的数量，这意味着所有spj实例都参与了一个查询的执行，事实上，一些spj实例可以（并且确实）从同一个查询接收多个请求。在ndb 7.6.4中，一个spj请求可以处理一组要扫描的根片段，因此只需要向每个节点上的任何给定spj实例（dbspj块）发送一个spj请求（scan_fragreq）。

Since DBSPJ consumes a relatively small amount of the total CPU used when evaluating a pushed join, unlike the LDM block (which is repsonsible for the majority of the CPU usage), introducing multiple SPJ blocks adds some parallelism, but the additional overhead also increases. By enabling a single SPJ request to handle a set of root fragments to be scanned, such that only a single SPJ request is sent to each DBSPJ instance on each node and batch sizes are allocated per fragment, the multi-fragment scan can obtain a larger total batch size, allowing for some scheduling optimizations to be done within the SPJ block, which can scan a single fragment at a time (giving it the total batch size allocation), scan all fragments in parallel using smaller sub-batches, or some combination of the two.

由于dbspj在计算pushd join时占用的cpu总量相对较少，与ldm块不同（ldm块对大多数cpu使用是可重复的），引入多个spj块会增加一些并行性，但额外的开销也会增加。通过启用单个spj请求来处理一组要扫描的根片段，这样每个节点上的每个dbspj实例只发送一个spj请求，并且每个片段分配批大小，多片段扫描可以获得更大的总批大小，从而允许在spj块内进行一些调度优化，这是可以一次扫描一个片段（为它分配总的批大小），使用较小的子批并行扫描所有片段，或两者的某种组合。

This work is expected to increase performance of pushed-down joins for the following reasons:

由于以下原因，此工作有望提高下推连接的性能：

Improved O_DIRECT handling for redo logs.  NDB 7.6.4 implements a new data node configuration parameter ODirectSyncFlag which causes completed redo log writes using O_DIRECT to be handled as fsync calls. ODirectSyncFlag is disabled by default; to enable it, set it to true.

改进了重做日志的o_直接处理。ndb 7.6.4实现了一个新的数据节点配置参数odirectsyncflag，它将使用o_direct完成的重做日志写入作为fsync调用处理。默认情况下，ODirectSyncFlag被禁用；若要启用它，请将其设置为true。

You should bear in mind that the setting for this parameter is ignored when at least one of the following conditions is true:

应记住，当至少满足以下条件之一时，将忽略此参数的设置：

Locking of CPUs to offline index build threads.  In NDB 7.6.4 and later, offline index builds by default use all cores available to ndbmtd, instead of being limited to the single core reserved for the I/O thread. It also becomes possible to specify a desired set of cores to be used for I/O threads performing offline multithreaded builds of ordered indexes. This can improve restart and restore times and performance, as well as availability.

将CPU锁定到脱机索引生成线程。在ndb 7.6.4及更高版本中，离线索引构建在默认情况下使用ndbmtd可用的所有核心，而不限于为i/o线程保留的单个核心。还可以指定用于I/O线程的所需内核集，以执行顺序索引的脱机多线程构建。这可以提高重启和恢复时间、性能以及可用性。

This improvement involves several related changes. The first of these is to change the default value for the BuildIndexThreads configuration parameter (from 0 to 128), means that offline ordered index builds are now multithreaded by default. The default value for the TwoPassInitialNodeRestartCopy is also changed (from false to true), so that an initial node restart first copies all data without any creation of indexes from a “live” node to the node which is being started, builds the ordered indexes offline after the data has been copied, then again synchronizes with the live node; this can significantly reduce the time required for building indexes. In addition, to facilitate explicit locking of offline index build threads to specific CPUs, a new thread type (idxbld) is defined for the ThreadConfig configuration parameter.

这种改进涉及到几个相关的变化。第一个是更改buildIndexThreads配置参数的默认值（从0更改为128），这意味着脱机排序的索引生成现在在默认情况下是多线程的。twopassinitialnoderestartcopy的默认值也被更改（从false更改为true），这样初始节点restart首先将所有数据从“活动”节点复制到正在启动的节点，而无需创建任何索引，在复制数据后脱机构建有序索引，然后再次与活动节点同步；这可以显著减少构建索引所需的时间。此外，为了方便将脱机索引生成线程显式锁定到特定CPU，为threadconfig配置参数定义了新的线程类型（idxbld）。

As part of this work, NDB can now distinguish between execution thread types and other types of threads, and between types of threads which are permanently assigned to specific tasks, and those whose assignments are merely temporary.

作为这项工作的一部分，ndb现在可以区分执行线程类型和其他类型的线程，以及永久分配给特定任务的线程类型和仅分配给临时任务的线程类型。

NDB 7.6.4 also introduces the nosend parameter for ThreadCOnfig. By setting this to 1, you can keep a main, ldm, rep, or tc thread from assisting the send threads. This parameter is 0 by default, and cannot be used with I/O threads, send threads, index build threads, or watchdog threads.

ndb 7.6.4还为threadconfig引入了nosend参数。通过将此设置为1，可以使main、ldm、rep或tc线程不协助发送线程。此参数默认为0，不能与I/O线程、发送线程、索引生成线程或看门狗线程一起使用。

For additonal information, see the descriptions of the parameters.

有关其他信息，请参见参数的说明。

Variable batch sizes for DDL bulk data operations.  As part of work ongoing to optimize bulk DDL performance by ndbmtd, it is now possible to obtain performance improvements by increasing the batch size for the bulk data parts of DDL operations processing data using scans. Batch sizes are now made configurable for unique index builds, foreign key builds, and online reorganization, by setting the respective data node configuration parameters listed here:

DDL批量数据操作的可变批处理大小。作为ndbmtd优化大容量ddl性能的工作的一部分，现在可以通过增加使用扫描处理数据的ddl操作的大容量数据部分的批大小来获得性能改进。通过设置下面列出的相应数据节点配置参数，现在可以为唯一索引生成、外键生成和联机重组配置批大小：

For each of the parameters just listed, the default value is 64, the minimum is 16, and the maximum is 512.

对于刚才列出的每个参数，默认值是64，最小值是16，最大值是512。

Increasing the appropriate batch size or sizes can help amortize inter-thread and inter-node latencies and make use of more parallel resources (local and remote) to help scale DDL performance. In each case there can be a tradeoff with ongoing traffic.

增加适当的批处理大小有助于分摊线程间和节点间的延迟，并利用更多的并行资源（本地和远程）来帮助扩展ddl性能。在每种情况下，都可以与正在进行的流量进行权衡。

Partial LCPs.  NDB 7.6.4 implements partial local checkpoints. Formerly, an LCP always made a copy of the entire database. When working with terabytes of data this process could require a great deal of time, with an adverse impact on node and cluster restarts especially, as well as more space for the redo logs. It is now no longer strictly necessary for LCPs to do this—instead, an LCP now by default saves only a number of records that is based on the quantity of data changed since the previous LCP. This can vary between a full checkpoint and a checkpoint that changes nothing at all. In the event that the checkpoint reflects any changes, the minimum is to write one part of the 2048 making up a local LCP.

部分LCP。ndb 7.6.4实现部分本地检查点。以前，LCP总是复制整个数据库。当使用兆字节的数据时，这个过程可能需要大量的时间，尤其是对节点和集群的重新启动有不利影响，并且需要更多的空间来存储重做日志。现在，lcp不再严格需要这样做，而是默认情况下，lcp只保存基于自上一个lcp以来更改的数据量的多个记录。这可以在完全检查点和完全不改变任何内容的检查点之间变化。在检查点反映任何更改的情况下，最小值是写入组成本地LCP的2048的一部分。

As part of this change, two new data node configuration parameters are inroduced in this release: EnablePartialLcp (default true, or enabled) enables partial LCPs. RecoveryWork controls the percentage of space given over to LCPs; it increases with the amount of work which must be performed on LCPs during restarts as opposed to that performed during normal operations. Raising this value causes LCPs during normal operations to require writing fewer records and so decreases the usual workload. Raising this value also means that restarts can take longer.

作为此更改的一部分，此版本中引入了两个新的数据节点配置参数：enablepartiallcp（默认为true或enabled）启用部分lcp。RecoveryWork控制分配给LCP的空间百分比；它随着在重新启动期间必须在LCP上执行的工作量而增加，而不是在正常操作期间执行的工作量。提高这个值会导致在正常操作期间lcp需要写更少的记录，从而减少通常的工作负载。提高此值还意味着重新启动可能需要更长的时间。

You must disable partial LCPs explicitly by setting EnablePartialLcp=false. This uses the least amount of disk, but also tends to maximize the write load for LCPs. To optimize for the lowest workload on LCPs during normal operation, use EnablePartialLcp=true and RecoveryWork=100. To use the least disk space for partial LCPs, but with bounded writes, use EnablePartialLcp=true and RecoveryWork=25, which is the minimum for RecoveryWork. The default is EnablePartialLcp=true with RecoveryWork=50, which means LCP files require approximately 1.5 times DataMemory; using CompressedLcp=1, this can be further reduced by half. Recovery times using the default settings should also be much faster than when EnablePartialLcp is set to false.

必须通过设置enablepartiallcp=false显式禁用部分lcp。这使用了最少的磁盘，但也趋向于最大化LCPS的写入负载。要在正常操作期间优化LCP上的最低工作负载，请使用enablepartiallcp=true和recoverywork=100。要为部分lcp使用最小的磁盘空间，但对有界写入，请使用enablepartiallcp=true和recoverywork=25，这是recoverywork的最小值。默认是EnabePealAlpCp= Trror具有恢复工作＝50，这意味着LCP文件需要大约1.5倍DATAMEMORY；使用压缩SELCP＝1，这可以进一步减少一半。使用默认设置的恢复时间也应该比enablepartiallcp设置为false时快得多。

In addition the data node configuration parameters BackupDataBufferSize, BackupWriteSize, and BackupMaxWriteSize are all now deprecated, and subject to removal in a future release of MySQL NDB Cluster.

此外，数据节点配置参数backupdateabuffersize、backupwritesize和backupmaxwritesize现在都已弃用，并将在mysql ndb cluster的未来版本中删除。

As part of this enhancement, work has been done to correct several issues with node restarts wherein it was possible to run out of undo log in various situations, most often when restoring a node that had been down for a long time during a period of intensive write activity.

作为此增强的一部分，已经完成了一些工作，以纠正节点重新启动时的几个问题，其中在各种情况下可能会耗尽撤消日志，最常见的情况是在还原在密集的写入活动期间长时间关闭的节点时。

Additional work was done to improve data node survival of long periods of synchronization without timing out, by updating the LCP watchdog during this process, and keeping better track of the progress of disk data synchronization. Previously, there was the possibility of spurious warnings or even node failures if synchronization took longer than the LCP watchdog timeout.

通过在同步过程中更新lcp看门狗，更好地跟踪磁盘数据同步的进程，在不超时的情况下提高了数据节点在长时间同步中的生存率。以前，如果同步时间超过lcp监视程序超时，则可能出现虚假警告，甚至节点故障。

Parallel undo log record processing.  Formerly, the data node LGMAN kernel block processed undo log records serially; now this is done in parallel. The rep thread, which hands off undo records to LDM threads, waited for an LDM to finish applying a record before fetching the next one; now the rep thread no longer waits, but proceeds immediately to the next record and LDM.

并行撤消日志记录处理。以前，数据节点lgman内核块串行处理undo日志记录；现在这是并行处理的。rep线程将撤消记录交给ldm线程，它等待ldm在获取下一条记录之前完成应用记录；现在rep线程不再等待，而是立即前进到下一条记录和ldm。

A count of the number of outstanding log records for each LDM in LGMAN is kept, and decremented whenever an LDM has completed the execution of a record. All the records belonging to a page are sent to the same LDM thread but are not guaranteed to be processed in order, so a hash map of pages that have outstanding records maintains a queue for each of these pages. When the page is available in the page cache, all records pending in the queue are applied in order.

lgman中每个ldm的未完成日志记录数的计数将被保留，并在ldm完成记录的执行时递减。属于一个页面的所有记录都被发送到同一个ldm线程，但不能保证按顺序处理，因此具有未完成记录的页面的哈希映射为这些页面中的每个页面维护一个队列。当页面在页面缓存中可用时，将按顺序应用队列中挂起的所有记录。

A few types of records continue to be processed serially: UNDO_LCP, UNDO_LCP_FIRST, UNDO_LOCAL_LCP, UNDO_LOCAL_LCP_FIRST, UNDO_DROP, and UNDO_END.

有几种类型的记录继续按顺序处理：undo_lcp、undo_lcp_first、undo_local_lcp、undo_local_lcp_first、undo_drop和undo_end。

There are no user-visible changes in functionality directly associated with this performance enhancement; it is part of the work being done to improve undo long handling in support of partial local checkpoints in NDB Cluster 7.6.4.

与此性能增强直接相关的功能中没有用户可见的更改；这是改进撤消长时间处理以支持ndb群集7.6.4中的部分本地检查点的工作的一部分。

Reading table and fragment IDs from extent for undo log applier.  When applying an undo log, it is necessary to obtain the table ID and fragment ID from the page ID. This was done previously by reading the page from the PGMAN kernel block using an extra PGMAN worker thread, but when applying the undo log it was necessary to read the page again.

正在从撤消日志应用程序的扩展数据块读取表和片段ID。应用撤消日志时，需要从页ID获取表ID和片段ID。这是以前通过使用额外的pgman工作线程从pgman内核块读取页来完成的，但在应用撤消日志时，需要再次读取页。

when using O_DIRECT this was very inefficient since the page was not cached in the OS kernel. To correct this issue, mapping from page ID to table ID and fragment ID is now done using information from the extent header the table IDs and fragment IDs for the pages used within a given extent. The extent pages are always present in the page cache, so no extra reads from disk are required for performing the mapping. In addition, the information can already be read, using existing TSMAN kernel block data structures.

当使用o_direct时，这是非常低效的，因为页面没有缓存在os内核中。要更正此问题，现在可以使用来自数据块头的信息完成从页id到表id和片段id的映射，这些信息来自给定数据块内使用的页的表id和片段id。扩展页始终存在于页缓存中，因此执行映射不需要从磁盘进行额外的读取。此外，可以使用现有的TMSN内核块数据结构来读取信息。

See the description of the ODirect data node configuration parameter, for more information.

有关详细信息，请参见odirect数据节点配置参数的说明。

NDB Cluster Auto-Installer improvements.  In NDB 7.6.4, node configuration parameters, their default values, and their documentation as found in the Auto-Installer have been better aligned with those found in NDB Cluster software releases. SSH support and configuration have also been improved. In addition, HTTPS is now used by default for Web connections, and cookies are no longer employed as a persistent data storage mechanism. More information about these and other changes in the Auto-Installer is given in the next several paragraphs.

ndb集群自动安装程序改进。在ndb 7.6.4中，节点配置参数、它们的默认值以及在自动安装程序中找到的文档与ndb集群软件版本中找到的更好地一致。ssh支持和配置也得到了改进。此外，https现在默认用于web连接，cookies不再用作持久数据存储机制。关于这些和自动安装程序中的其他更改的更多信息将在接下来的几段中给出。

The Auto-Installer now implements a mechanism for setting configuration parameters that take discrete values. For example, the data node parameter Arbitration must now be set to one of its allowed values Default, Disabled, or WaitExternal.

自动安装程序现在实现了一种设置获取离散值的配置参数的机制。例如，数据节点参数仲裁现在必须设置为其允许的值之一default、disabled或waitexternal。

The Auto-Installer also now gets and shows the amount of disk space available per host to the cluster (as DiskFree), using this information to obtain realistic values for configuration parameters that depend on it.

自动安装程序现在还可以获取并显示集群中每个主机的可用磁盘空间量（作为diskfree），并使用此信息获取依赖于它的配置参数的实际值。

Secure connection support in the MySQL NDB Cluster Auto-Installer has been updated or improved in NDB Cluster 7.6.4 as follows:

mysql ndb cluster auto installer中的安全连接支持在ndb cluster 7.6.4中更新或改进如下：

Other enhancements relating to data security that are implemented in NDB 7.6.4 include the following:

在ndb 7.6.4中实现的与数据安全相关的其他增强包括：

See Section 21.2.1, “The NDB Cluster Auto-Installer (NDB 7.5)”, for more information.

有关详细信息，请参阅第21.2.1节“ndb群集自动安装程序（ndb 7.5）”。

Shared memory transporter.  User-defined shared memory (SHM) connections between a data node and an API node on the same host computer are supported in NDB 7.6.6 and later, and are no longer considered experimental. You can enable an explicit shared memory connection by setting the UseShm configuration parameter to 1 for the relevant data node. When explicitly defining shared memory as the connection method, it is also necessary that both the data node and the API node are identified by HostName.

共享内存传输程序。ndb 7.6.6及更高版本支持在同一主机上的数据节点和api节点之间的用户定义的共享内存（shm）连接，并且不再被认为是实验性的。通过将相关数据节点的useshm配置参数设置为1，可以启用显式共享内存连接。当显式地将共享内存定义为连接方法时，还需要使用主机名来标识数据节点和api节点。

Performance of SHM connections can be enhanced through setting parameters such as ShmSize, ShmSpintime, and SendBufferMemory in an [shm] or [shm default] section of the cluster configuration file (config.ini). Configuration of SHM is otherwise similar to that of the TCP transporter.

可以通过在群集配置文件（config.ini）的[shm]或[shm default]部分设置shmsize、shmspintime和sendbuffermemory等参数来提高shm连接的性能。SHM的配置与TCP传输程序的配置类似。

The SigNum parameter is not used in the new SHM implementation, and any settings made for it are now ignored. Section 21.3.3.12, “NDB Cluster Shared Memory Connections”, provides more information about these parameters. In addition, as part of this work, NDB code relating to the old SCI transporter has been removed.

signum参数未在新的shm实现中使用，为它所做的任何设置现在都将被忽略。第21.3.3.12节“ndb集群共享内存连接”提供了有关这些参数的更多信息。此外，作为这项工作的一部分，与旧的sci转运体相关的ndb代码已经被删除。

For more information, see Section 21.3.3.12, “NDB Cluster Shared Memory Connections”.

有关更多信息，请参阅第21.3.3.12节“ndb集群共享内存连接”。

SPJ block inner join optimization.  In NDB 7.6.6 and later, the SPJ kernel block can take into account when it is evaluating a join request in which at least some of the tables are INNER-joined. This means that it can eliminate requests for row, ranges, or both as soon as it becomes known that one or more of the preceding requests did not return any results for a parent row. This saves both the data nodes and the SPJ block from having to handle requests and result rows which never take part in an INNER-joined result row.

spj块内部连接优化。在ndb 7.6.6及更高版本中，spj内核块在计算至少有一些表是内部连接的连接请求时可以将其考虑在内。这意味着，一旦知道前面的一个或多个请求没有返回父行的任何结果，它就可以消除对行、范围或两者的请求。这样就避免了数据节点和spj块必须处理从不参与内部联接结果行的请求和结果行。

Consider this join query, where pk is the primary key on tables t2, t3, and t4, and columns x, y, and z are nonindexed columns:

考虑这个连接查询，其中pk是表t2、t3和t4上的主键，而x、y和z列是非索引列：

SELECT * FROM t1
  JOIN t2 ON t2.pk = t1.x
  JOIN t3 ON t3.pk = t1.y
  JOIN t4 ON t4.pk = t1.z;

Previously, this resulted in an SPJ request including a scan on table t1, and lookups on each of the tables t2, t3, and t4; these were evaluated for every row returned from t1. For these, SPJ created LQHKEYREQ requests for tables t2, t3, and t4. Now SPJ takes into consideration the requirement that, to produce any result rows, an inner join must find a match in all tables joined; as soon as no matches are found for one of the tables, any further requests to tables having the same parent or tables are now skipped.

以前，这导致spj请求，包括对表t1的扫描，以及对表t2、t3和t4中的每一个表的查找；这些都是针对从t1返回的每一行计算的。为此，spj为表t2、t3和t4创建了lqhkeyreq请求。现在spj考虑到了这样一个要求：要生成任何结果行，内部联接必须在所有联接的表中找到匹配项；一旦没有找到其中一个表的匹配项，就立即跳过对具有相同父表的表的任何进一步请求。

NDB wakeup thread.  NDB uses a poll receiver to read from sockets, to execute messages from the sockets, and to wake up other threads. When making only intermittent use of a receive thread, poll ownership is given up before starting to wake up other threads, which provides some degree of parallelism in the receive thread, but, when making constant use of the receive thread, the thread can be overburdened by tasks including wakeup of other threads.

ndb唤醒线程。ndb使用轮询接收器读取套接字，执行来自套接字的消息，并唤醒其他线程。当只间歇使用接收线程时，在唤醒其他线程之前会放弃轮询所有权，这会在接收线程中提供某种程度的并行性，但是，当持续使用接收线程时，线程可能会被包括唤醒其他线程在内的任务负担过重。

NDB 7.6.6 and later supports offloading by the receiver thread of the task of waking up other threads to a new thread that wakes up other threads on request (and otherwise simply sleeps), making it possible to improve the capacity of a single cluster connection by roughly ten to twenty percent.

ndb 7.6.6及更高版本支持接收器线程将唤醒其他线程的任务卸载到一个新线程，该线程根据请求唤醒其他线程（否则只是休眠），从而可以将单个群集连接的容量提高大约10%到20%。

Adaptive LCP control.  NDB 7.6.7 implements an adaptive LCP control mechanism which acts in response to changes in redo log space usage. By controlling LCP disk write speed, you can help protect against a number of resource-related issues, including the following:

自适应LCP控制。ndb 7.6.7实现了一种自适应的lcp控制机制，该机制对重做日志空间使用量的变化做出响应。通过控制LCP磁盘写入速度，您可以帮助防止许多与资源相关的问题，包括以下问题：

This work includes the following changes relating to NDB configuration parameters:

这项工作包括以下与ndb配置参数有关的更改：

This work implements control of LCP speed chiefly to minimize the risk of running out of redo log. This is done in adapative fashion, based on the amount of redo log space used, using the alert levels, with the responses taken when these levels are attained, shown here:

这项工作主要是为了将重做日志耗尽的风险降到最低。这是以自适应方式完成的，基于使用的重做日志空间量，使用警报级别，并在达到这些级别时执行响应，如下所示：

Raising the level also has the effect of increasing the calculated target checkpoint speed.

提高级别还可以提高计算的目标检查点速度。

LCP control has the following benefits for NDB installations:

对于ndb安装，lcp控制有以下好处：

ndb_restore options.  Beginning with NDB 7.6.9, the --nodeid and --backupid options are both required when invoking ndb_restore.

ndb_还原选项。从ndb 7.6.9开始，--nodeid和--backupid选项在调用ndb_restore时都是必需的。

Node Configuration Parameters Introduced in NDB 7.5

ndb 7.5中引入的节点配置参数

Node Configuration Parameters Deprecated in NDB 7.5

ndb 7.5中不推荐使用的节点配置参数

Node Configuration Parameters Removed in NDB 7.5

在ndb 7.5中删除的节点配置参数

MySQL Server Options and Variables Introduced in NDB 7.5

ndb 7.5中引入的mysql服务器选项和变量

MySQL Server Options and Variables Deprecated in NDB 7.5

ndb 7.5中不推荐使用mysql服务器选项和变量

MySQL Server Options and Variables Removed in NDB 7.5

ndb 7.5中删除的mysql服务器选项和变量

Node Configuration Parameters Introduced in NDB 7.6

ndb 7.6中引入的节点配置参数

Node Configuration Parameters Deprecated in NDB 7.6

在ndb 7.6中不推荐使用的节点配置参数

Node Configuration Parameters Removed in NDB 7.6

在ndb 7.6中删除的节点配置参数

MySQL Server Options and Variables Introduced in NDB 7.6

ndb 7.6中引入的mysql服务器选项和变量

MySQL Server Options and Variables Deprecated in NDB 7.6

ndb 7.6中不推荐使用mysql服务器选项和变量

MySQL Server Options and Variables Removed in NDB 7.6

ndb 7.6中删除的mysql服务器选项和变量

Temporary tables.  Temporary tables are not supported. Trying either to create a temporary table that uses the NDB storage engine or to alter an existing temporary table to use NDB fails with the error Table storage engine 'ndbcluster' does not support the create option 'TEMPORARY'.

临时表。不支持临时表。尝试创建一个临时表，该表使用不可修改的存储引擎或更改现有的临时表，以使用错误。

Indexes and keys in NDB tables.  Keys and indexes on NDB Cluster tables are subject to the following limitations:

ndb表中的索引和键。ndb集群表上的键和索引受以下限制：

Restrictions on foreign keys.  Support for foreign key constraints in NDB 7.5 is comparable to that provided by InnoDB, subject to the following restrictions:

外键限制。ndb 7.5中对外键约束的支持与innodb提供的支持类似，但受到以下限制：

For more information, see Section 13.1.18.6, “Using FOREIGN KEY Constraints”, and Section 1.8.3.2, “FOREIGN KEY Constraints”.

有关详细信息，请参见第13.1.18.6节“使用外键约束”和第1.8.3.2节“外键约束”。

NDB Cluster and geometry data types.  Geometry data types (WKT and WKB) are supported for NDB tables. However, spatial indexes are not supported.

ndb集群和几何数据类型。ndb表支持几何数据类型（wkt和wkb）。但是，不支持空间索引。

Character sets and binary log files.  Currently, the ndb_apply_status and ndb_binlog_index tables are created using the latin1 (ASCII) character set. Because names of binary logs are recorded in this table, binary log files named using non-Latin characters are not referenced correctly in these tables. This is a known issue, which we are working to fix. (Bug #50226)

字符集和二进制日志文件。目前，ndb_apply_status和ndb_binlog_索引表是使用latin1（ascii）字符集创建的。由于此表中记录了二进制日志的名称，因此这些表中未正确引用使用非拉丁字符命名的二进制日志文件。这是一个已知的问题，我们正在努力解决。（错误50226）

To work around this problem, use only Latin-1 characters when naming binary log files or setting any the --basedir, --log-bin, or --log-bin-index options.

若要解决此问题，请在命名二进制日志文件或设置任何--basedir、--log bin或--log bin索引选项时仅使用拉丁文-1字符。

Creating NDB tables with user-defined partitioning.  Support for user-defined partitioning in NDB Cluster is restricted to [LINEAR] KEY partitioning. Using any other partitioning type with ENGINE=NDB or ENGINE=NDBCLUSTER in a CREATE TABLE statement results in an error.

使用用户定义的分区创建ndb表。ndb集群中对用户定义分区的支持仅限于[线性]键分区。在CREATE TABLE语句中使用ENGINE=ndb或ENGINE=ndbcluster的任何其他分区类型都会导致错误。

It is possible to override this restriction, but doing so is not supported for use in production settings. For details, see User-defined partitioning and the NDB storage engine (NDB Cluster).

可以覆盖此限制，但不支持在生产设置中使用。有关详细信息，请参阅用户定义分区和ndb存储引擎（ndb集群）。

Default partitioning scheme.  All NDB Cluster tables are by default partitioned by KEY using the table's primary key as the partitioning key. If no primary key is explicitly set for the table, the “hidden” primary key automatically created by the NDB storage engine is used instead. For additional discussion of these and related issues, see Section 22.2.5, “KEY Partitioning”.

默认分区方案。默认情况下，所有ndb集群表都是按键分区的，使用表的主键作为分区键。如果没有为表显式设置主键，则使用由ndb存储引擎自动创建的“隐藏”主键。有关这些问题和相关问题的更多讨论，请参见第22.2.5节“密钥分区”。

CREATE TABLE and ALTER TABLE statements that would cause a user-partitioned NDBCLUSTER table not to meet either or both of the following two requirements are not permitted, and fail with an error:

CREATE TABLE和ALTER TABLE语句将导致用户分区的ndbcluster表不满足以下两个要求中的任何一个或同时满足这两个要求，这是不允许的，并且会失败并出现错误：

Exception.  If a user-partitioned NDBCLUSTER table is created using an empty column-list (that is, using PARTITION BY [LINEAR] KEY()), then no explicit primary key is required.

例外。如果使用空列列表（即，使用[Real[Krim]键（））来创建用户分区的NDCBROCH表，则不需要显式主键。

Maximum number of partitions for NDBCLUSTER tables.  The maximum number of partitions that can defined for a NDBCLUSTER table when employing user-defined partitioning is 8 per node group. (See Section 21.1.2, “NDB Cluster Nodes, Node Groups, Replicas, and Partitions”, for more information about NDB Cluster node groups.

NdBaseCopyTabes的最大分区数。在使用用户定义分区时，可为每个节点组定义8个分区的最大分区数。（有关ndb群集节点组的详细信息，请参阅第21.1.2节“ndb群集节点、节点组、副本和分区”。

DROP PARTITION not supported.  It is not possible to drop partitions from NDB tables using ALTER TABLE ... DROP PARTITION. The other partitioning extensions to ALTER TABLE—ADD PARTITION, REORGANIZE PARTITION, and COALESCE PARTITION—are supported for NDB tables, but use copying and so are not optimized. See Section 22.3.1, “Management of RANGE and LIST Partitions” and Section 13.1.8, “ALTER TABLE Syntax”.

不支持删除分区。无法使用alter table从ndb表中删除分区…下拉分区。NDB表支持更改表添加分区、重新组织分区和合并分区的其他分区扩展，但使用复制并没有优化。参见第22.3.1节“范围和列表分区的管理”和第13.1.8节“更改表语法”。

Row-based replication.  When using row-based replication with NDB Cluster, binary logging cannot be disabled. That is, the NDB storage engine ignores the value of sql_log_bin.

基于行的复制。对ndb集群使用基于行的复制时，不能禁用二进制日志记录。也就是说，ndb存储引擎忽略sql_log_bin的值。

JSON data type.  The MySQL JSON data type is supported for NDB tables in the mysqld supplied with NDB 7.5.2 and later.

JSON数据类型。ndb 7.5.2及更高版本提供的mysqld中的ndb表支持mysql json数据类型。

An NDB table can have a maximum of 3 JSON columns.

NDB表最多可以有3个JSON列。

The NDB API has no special provision for working with JSON data, which it views simply as BLOB data. Handling data as JSON must be performed by the application.

ndb api没有处理json数据的特殊规定，它只是将其视为blob数据。作为json处理数据必须由应用程序执行。

CPU and thread info ndbinfo tables.  NDB 7.5.2 adds several new tables to the ndbinfo information database providing information about CPU and thread activity by node, thread ID, and thread type. The tables are listed here:

CPU和线程信息ndbinfo表。ndb 7.5.2将几个新表添加到ndbinfo信息数据库中，按节点、线程id和线程类型提供有关cpu和线程活动的信息。表格如下：

For more information about these tables, see Section 21.5.10, “ndbinfo: The NDB Cluster Information Database”.

有关这些表的更多信息，请参阅21.5.10节，“ndbinfo:ndb集群信息数据库”。

Lock info ndbinfo tables.  NDB 7.5.3 adds new tables to the ndbinfo information database providing information about locks and lock attempts in a running NDB Cluster. These tables are listed here:

锁定信息ndbinfo表。ndb 7.5.3将新表添加到ndbinfo信息数据库中，提供有关正在运行的ndb集群中的锁和锁尝试的信息。这些表格如下：

A DELETE statement on an NDB table makes the memory formerly used by the deleted rows available for re-use by inserts on the same table only. However, this memory can be made available for general re-use by performing OPTIMIZE TABLE.

ndb表上的delete语句使以前由已删除行使用的内存只能由同一表上的insert重用。但是，可以通过执行优化表使该内存可供一般重用。

A rolling restart of the cluster also frees any memory used by deleted rows. See Section 21.5.5, “Performing a Rolling Restart of an NDB Cluster”.

集群的滚动重新启动还释放了被删除行使用的任何内存。参见第21.5.5节“执行ndb集群的滚动重启”。

A DROP TABLE or TRUNCATE TABLE operation on an NDB table frees the memory that was used by this table for re-use by any NDB table, either by the same table or by another NDB table.

对ndb表执行drop table或truncate table操作可释放此表使用的内存，供任何ndb表（同一个表或另一个ndb表）重用。

Limits imposed by the cluster's configuration.  A number of hard limits exist which are configurable, but available main memory in the cluster sets limits. See the complete list of configuration parameters in Section 21.3.3, “NDB Cluster Configuration Files”. Most configuration parameters can be upgraded online. These hard limits include:

群集配置所施加的限制。存在许多可配置的硬限制，但集群中可用的主内存设置了限制。请参阅21.3.3节“ndb群集配置文件”中配置参数的完整列表。大多数配置参数都可以在线升级。这些硬限制包括：

Node and data object maximums.  The following limits apply to numbers of cluster nodes and metadata objects:

节点和数据对象最大值。以下限制适用于群集节点和元数据对象的数量：

See Previous NDB Cluster Issues Resolved in NDB Cluster 7.3, for more information.

有关详细信息，请参阅ndb cluster 7.3中以前解决的ndb集群问题。

Transaction isolation level.  The NDBCLUSTER storage engine supports only the READ COMMITTED transaction isolation level. (InnoDB, for example, supports READ COMMITTED, READ UNCOMMITTED, REPEATABLE READ, and SERIALIZABLE.) You should keep in mind that NDB implements READ COMMITTED on a per-row basis; when a read request arrives at the data node storing the row, what is returned is the last committed version of the row at that time.

事务隔离级别。ndbcluster存储引擎仅支持读取提交的事务隔离级别。（例如，innodb支持read committed、read uncommitted、repeatable read和serializable。）您应该记住，ndb在每行的基础上实现read committed；当读请求到达存储该行的数据节点时，返回的是该行当时的最后一个提交版本。

Uncommitted data is never returned, but when a transaction modifying a number of rows commits concurrently with a transaction reading the same rows, the transaction performing the read can observe “before” values, “after” values, or both, for different rows among these, due to the fact that a given row read request can be processed either before or after the commit of the other transaction.

从未返回未提交的数据，但当修改多行的事务与读取相同行的事务同时提交时，执行读取的事务可以观察到其中不同行的“before”值、“after”值或两者，因为可以处理给定的行读取请求在提交其他事务之前或之后。

To ensure that a given transaction reads only before or after values, you can impose row locks using SELECT ... LOCK IN SHARE MODE. In such cases, the lock is held until the owning transaction is committed. Using row locks can also cause the following issues:

为了确保给定事务只在值之前或之后读取，可以使用select…锁定在共享模式。在这种情况下，锁将一直保持到提交所属事务为止。使用行锁还可能导致以下问题：

NDB uses READ COMMITTED for all reads unless a modifier such as LOCK IN SHARE MODE or FOR UPDATE is used. LOCK IN SHARE MODE causes shared row locks to be used; FOR UPDATE causes exclusive row locks to be used. Unique key reads have their locks upgraded automatically by NDB to ensure a self-consistent read; BLOB reads also employ extra locking for consistency.

ndb对所有读取使用read committed，除非使用诸如lock in share mode或for update之类的修饰符。共享模式下的锁导致使用共享行锁；更新导致使用排他行锁。唯一密钥读取会由ndb自动升级其锁，以确保自一致性读取；blob读取还会使用额外的锁来保持一致性。

See Section 21.5.3.4, “NDB Cluster Backup Troubleshooting”, for information on how NDB Cluster's implementation of transaction isolation level can affect backup and restoration of NDB databases.

有关ndb集群执行事务隔离级别如何影响ndb数据库备份和恢复的信息，请参阅第21.5.3.4节“ndb集群备份故障排除”。

Transactions and BLOB or TEXT columns.  NDBCLUSTER stores only part of a column value that uses any of MySQL's BLOB or TEXT data types in the table visible to MySQL; the remainder of the BLOB or TEXT is stored in a separate internal table that is not accessible to MySQL. This gives rise to two related issues of which you should be aware whenever executing SELECT statements on tables that contain columns of these types:

事务和blob或文本列。ndbcluster只在mysql可见的表中存储使用mysql的blob或文本数据类型的列值的一部分；blob或文本的其余部分存储在mysql无法访问的单独内部表中。这会导致两个相关问题，在对包含这些类型的列的表执行select语句时，应注意这些问题：

Rollbacks.  There are no partial transactions, and no partial rollbacks of transactions. A duplicate key or similar error causes the entire transaction to be rolled back.

回滚。不存在部分事务，也不存在事务的部分回滚。重复的密钥或类似错误会导致整个事务回滚。

This behavior differs from that of other transactional storage engines such as InnoDB that may roll back individual statements.

这种行为与其他事务性存储引擎（如innodb）的行为不同，后者可能回滚单个语句。

Transactions and memory usage.  As noted elsewhere in this chapter, NDB Cluster does not handle large transactions well; it is better to perform a number of small transactions with a few operations each than to attempt a single large transaction containing a great many operations. Among other considerations, large transactions require very large amounts of memory. Because of this, the transactional behavior of a number of MySQL statements is affected as described in the following list:

事务和内存使用。如本章其他部分所述，ndb集群不能很好地处理大型事务；与其尝试包含大量操作的单个大型事务，不如执行多个小事务，每个事务都有几个操作。在其他考虑因素中，大型事务需要非常大的内存。因此，许多mysql语句的事务行为会受到影响，如下表所示：

Transactions and the COUNT() function.  When using NDB Cluster Replication, it is not possible to guarantee the transactional consistency of the COUNT() function on the slave. In other words, when performing on the master a series of statements (INSERT, DELETE, or both) that changes the number of rows in a table within a single transaction, executing SELECT COUNT(*) FROM table queries on the slave may yield intermediate results. This is due to the fact that SELECT COUNT(...) may perform dirty reads, and is not a bug in the NDB storage engine. (See Bug #31321 for more information.)

事务和count（）函数。使用ndb群集复制时，无法保证从机上count（）函数的事务一致性。换言之，在主机上执行一系列语句（insert、delete或both）以更改单个事务中表中的行数时，在从机上执行表查询中的select count（*）可能会产生中间结果。这是因为select count（…）可能执行脏读，而不是ndb存储引擎中的错误。（有关详细信息，请参见Bug 31321。）

Temporary errors.  When first starting a node, it is possible that you may see Error 1204 Temporary failure, distribution changed and similar temporary errors.

临时错误。第一次启动节点时，可能会看到错误1204临时故障、分发已更改和类似的临时错误。

Errors due to node failure.  The stopping or failure of any data node can result in a number of different node failure errors. (However, there should be no aborted transactions when performing a planned shutdown of the cluster.)

节点故障导致的错误。任何数据节点的停止或故障都可能导致许多不同的节点故障错误。（但是，在执行计划关闭群集时，不应中止事务。）

Database and table names.  When using the NDB storage engine, the maximum allowed length both for database names and for table names is 63 characters. A statement using a database name or table name longer than this limit fails with an appropriate error.

数据库和表名。在使用NDB存储引擎时，数据库名称和表名的最大允许长度为63个字符。使用超过此限制的数据库名或表名的语句将失败，并出现相应的错误。

Number of database objects.  The maximum number of all NDB database objects in a single NDB Cluster—including databases, tables, and indexes—is limited to 20320.

数据库对象数。包括数据库、表和索引在内的单个NDB集群中所有NDB数据库对象的最大数量限制为20320个。

Attributes per table.  The maximum number of attributes (that is, columns and indexes) that can belong to a given table is 512.

每个表的属性。可以属于给定表的属性（即，列和索引）的最大数目是512。

Attributes per key.  The maximum number of attributes per key is 32.

每个键的属性。每个密钥的最大属性数是32个。

Row size.  The maximum permitted size of any one row is 14000 bytes.

行大小。任何一行的最大允许大小是14000字节。

Each BLOB or TEXT column contributes 256 + 8 = 264 bytes to this total; see String Type Storage Requirements, for more information relating to these types.

每个blob或text列都会为此总计贡献256+8=264个字节；有关这些类型的更多信息，请参阅字符串类型存储要求。

In addition, the maximum offset for a fixed-width column of an NDB table is 8188 bytes; attempting to create a table that violates this limitation fails with NDB error 851 Maximum offset for fixed-size columns exceeded. For memory-based columns, you can work around this limitation by using a variable-width column type such as VARCHAR or defining the column as COLUMN_FORMAT=DYNAMIC; this does not work with columns stored on disk. For disk-based columns, you may be able to do so by reordering one or more of the table's disk-based columns such that the combined width of all but the disk-based column defined last in the CREATE TABLE statement used to create the table does not exceed 8188 bytes, less any possible rounding performed for some data types such as CHAR or VARCHAR; otherwise it is necessary to use memory-based storage for one or more of the offending column or columns instead.

此外，NDB表的固定宽度列的最大偏移量为8188字节；试图创建违反此限制的表以NDB错误851失败，超出了固定大小列的最大偏移量。对于基于内存的列，可以通过使用可变宽度的列类型（如varchar）或将列定义为column_format=dynamic来解决此限制；这不适用于存储在磁盘上的列。对于基于磁盘的列，您可以通过重新排序表的一个或多个基于磁盘的列来完成此操作，以便用于创建表的CREATE TABLE语句中最后定义的除基于磁盘的列之外的所有列的组合宽度都不超过8188字节，减去对某些数据类型（如char或varchar）执行的任何可能的舍入；否则，必须对一个或多个有问题的列使用基于内存的存储。

BIT column storage per table.  The maximum combined width for all BIT columns used in a given NDB table is 4096.

每个表的位列存储。给定NDB表中使用的所有位列的最大组合宽度为4096。

FIXED column storage.  NDB Cluster 7.5 and later supports a maximum of 128 TB per fragment of data in FIXED columns. (Previously, this was 16 GB.)

固定柱存储。NDB集群7.5和以后支持在固定列中每个数据片段最多128个TB。（以前，这是16 GB。）

Index prefixes.  Prefixes on indexes are not supported for NDB tables. If a prefix is used as part of an index specification in a statement such as CREATE TABLE, ALTER TABLE, or CREATE INDEX, the prefix is not created by NDB.

索引前缀。ndb表不支持索引上的前缀。如果前缀用作语句（如CREATE TABLE、ALTER TABLE或CREATE INDEX）中索引规范的一部分，则前缀不是由ndb创建的。

A statement containing an index prefix, and creating or modifying an NDB table, must still be syntactically valid. For example, the following statement always fails with Error 1089 Incorrect prefix key; the used key part isn't a string, the used length is longer than the key part, or the storage engine doesn't support unique prefix keys, regardless of storage engine:

包含索引前缀并创建或修改ndb表的语句在语法上必须仍然有效。例如，以下语句总是失败，错误为1089前缀键不正确；使用的密钥部分不是字符串，使用的长度比密钥部分长，或者存储引擎不支持唯一的前缀键，无论存储引擎如何：

CREATE TABLE t1 (
    c1 INT NOT NULL,
    c2 VARCHAR(100),
    INDEX i1 (c2(500))
);

This happens on account of the SQL syntax rule that no index may have a prefix larger than itself.

这是由于sql语法规则，即任何索引的前缀都不能大于其本身。

Savepoints and rollbacks.  Savepoints and rollbacks to savepoints are ignored as in MyISAM.

保存点和回滚。保存点和对保存点的回滚在myisam中被忽略。

Durability of commits.  There are no durable commits on disk. Commits are replicated, but there is no guarantee that logs are flushed to disk on commit.

承诺的持久性。磁盘上没有持久提交。提交将被复制，但不能保证日志在提交时刷新到磁盘。

Replication.  Statement-based replication is not supported. Use --binlog-format=ROW (or --binlog-format=MIXED) when setting up cluster replication. See Section 21.6, “NDB Cluster Replication”, for more information.

复制。不支持基于语句的复制。设置群集复制时使用--binlog format=row（或--binlog format=mixed）。有关详细信息，请参阅21.6节“NDB群集复制”。

Replication using global transaction identifiers (GTIDs) is not compatible with NDB Cluster, and is not supported in NDB Cluster 7.5 or NDB CLuster 7.6. Do not enable GTIDs when using the NDB storage engine, as this is very likely to cause problems up to and including failure of NDB Cluster Replication.

使用全局事务标识符（gtid）的复制与ndb群集不兼容，并且在ndb群集7.5或ndb群集7.6中不受支持。使用ndb存储引擎时不要启用gtids，因为这很可能会导致ndb群集复制失败（包括失败）。

Semisynchronous replication is not supported in NDB Cluster.

ndb群集不支持半同步复制。

Generated columns.  The NDB storage engine does not support indexes on virtual generated columns.

生成的列。ndb存储引擎不支持虚拟生成列上的索引。

As with other storage engines, you can create an index on a stored generated column, but you should bear in mind that NDB uses DataMemory for storage of the generated column as well as IndexMemory for the index. See JSON columns and indirect indexing in NDB Cluster, for an example.

与其他存储引擎一样，您可以在存储的生成列上创建索引，但您应该记住，ndb使用datamemory存储生成列，并使用indexmemory存储索引。举一个例子，在NDB集群中看到JSON列和间接索引。

NDB Cluster writes changes in stored generated columns to the binary log, but does log not those made to virtual columns. This should not effect NDB Cluster Replication or replication between NDB and other MySQL storage engines.

ndb cluster将存储的生成列中的更改写入二进制日志，但不记录对虚拟列所做的更改。这不应影响ndb集群复制或ndb与其他mysql存储引擎之间的复制。

Range scans.  There are query performance issues due to sequential access to the NDB storage engine; it is also relatively more expensive to do many range scans than it is with either MyISAM or InnoDB.

范围扫描。由于对ndb存储引擎的顺序访问，存在查询性能问题；与myisam或innodb相比，执行许多范围扫描的成本也相对较高。

Reliability of Records in range.  The Records in range statistic is available but is not completely tested or officially supported. This may result in nonoptimal query plans in some cases. If necessary, you can employ USE INDEX or FORCE INDEX to alter the execution plan. See Section 8.9.4, “Index Hints”, for more information on how to do this.

范围内记录的可靠性。范围统计中的记录是可用的，但没有完全测试或官方支持。在某些情况下，这可能会导致非最优查询计划。如果需要，可以使用use index或force index来更改执行计划。有关如何执行此操作的详细信息，请参见第8.9.4节“索引提示”。

Unique hash indexes.  Unique hash indexes created with USING HASH cannot be used for accessing a table if NULL is given as part of the key.

唯一哈希索引。如果键的一部分为空，则使用哈希创建的唯一哈希索引不能用于访问表。

Machine architecture.  All machines used in the cluster must have the same architecture. That is, all machines hosting nodes must be either big-endian or little-endian, and you cannot use a mixture of both. For example, you cannot have a management node running on a PowerPC which directs a data node that is running on an x86 machine. This restriction does not apply to machines simply running mysql or other clients that may be accessing the cluster's SQL nodes.

机器架构。群集中使用的所有计算机必须具有相同的体系结构。也就是说，承载节点的所有计算机都必须是大端或小端，并且不能同时使用这两者。例如，不能让管理节点在powerpc上运行，而powerpc会指示在x86计算机上运行的数据节点。此限制不适用于仅运行MySQL或其他可能正在访问群集SQL节点的客户端的计算机。

Binary logging.  NDB Cluster has the following limitations or restrictions with regard to binary logging:

二进制日志记录。对于二进制日志记录，ndb集群有以下限制：

Schema operations (DDL statements) are rejected while any data node restarts.

架构操作（DDL语句）在任何数据节点重新启动时被拒绝。

Number of replicas.  The number of replicas, as determined by the NoOfReplicas data node configuration parameter, is the number of copies of all data stored by NDB Cluster. Setting this parameter to 1 means there is only a single copy; in this case, no redundancy is provided, and the loss of a data node entails loss of data. To guarantee redundancy, and thus preservation of data even if a data node fails, set this parameter to 2, which is the default and recommended value in production.

副本数。noofreplicas data node configuration参数确定的副本数是ndb集群存储的所有数据的副本数。将此参数设置为1意味着只有一个副本；在这种情况下，不提供冗余，数据节点的丢失会导致数据丢失。为了保证冗余，从而即使数据节点出现故障也能保存数据，请将此参数设置为2，这是生产中的默认值和建议值。

Setting NoOfReplicas to a value greater than 2 is possible (to a maximum of 4) but unnecessary to guard against loss of data. In addition, values greater than 2 for this parameter are not supported in production.

将NOF副本设置为大于2的值是可能的（最多为4），但不需要防止数据丢失。此外，生产中不支持此参数的值大于2。

Maximum number of tablespaces: 2³² (4294967296)

表空间的最大数目：232（4294967296）

Maximum number of data files per tablespace: 2¹⁶ (65536)

每个表空间的最大数据文件数：216（65536）

The minimum and maximum possible sizes of extents for tablespace data files are 32K and 2G, respectively. See Section 13.1.19, “CREATE TABLESPACE Syntax”, for more information.

表空间数据文件的最小和最大可能的扩展大小分别为32 K和2G。有关详细信息，请参阅第13.1.19节“创建表空间语法”。

Data files use DataMemory. Usage is the same as for in-memory data.

数据文件使用数据内存。用法与内存中的数据相同。

Data files use file descriptors. It is important to keep in mind that data files are always open, which means the file descriptors are always in use and cannot be re-used for other system tasks.

数据文件使用文件描述符。必须记住，数据文件总是打开的，这意味着文件描述符总是在使用，不能再用于其他系统任务。

Extents require sufficient DiskPageBufferMemory; you must reserve enough for this parameter to account for all memory used by all extents (number of extents times size of extents).

扩展数据块需要足够的diskpagebuffermemory；您必须保留足够的内存，以便此参数能够占用所有扩展数据块使用的所有内存（扩展数据块数乘以扩展数据块大小）。

No distributed table locks.  A LOCK TABLES works only for the SQL node on which the lock is issued; no other SQL node in the cluster “sees” this lock. This is also true for a lock issued by any statement that locks tables as part of its operations. (See next item for an example.)

没有分布式表锁。锁表只适用于发出锁的sql节点；集群中没有其他sql节点“看到”此锁。对于任何将表锁定为其操作一部分的语句发出的锁，也是如此。（请参见下一项以获取示例。）

ALTER TABLE operations.  ALTER TABLE is not fully locking when running multiple MySQL servers (SQL nodes). (As discussed in the previous item, NDB Cluster does not support distributed table locks.)

更改表操作。当运行多个mysql服务器（sql节点）时，alter table没有完全锁定。（如前一项所述，ndb集群不支持分布式表锁。）

If any of the management servers are running on the same host, you must give nodes explicit IDs in connection strings because automatic allocation of node IDs does not work across multiple management servers on the same host. This is not required if every management server resides on a different host.

如果任何管理服务器在同一主机上运行，则必须在连接字符串中为节点提供显式ID，因为节点ID的自动分配在同一主机上的多个管理服务器上不起作用。如果每个管理服务器都位于不同的主机上，则不需要这样做。

When a management server starts, it first checks for any other management server in the same NDB Cluster, and upon successful connection to the other management server uses its configuration data. This means that the management server --reload and --initial startup options are ignored unless the management server is the only one running. It also means that, when performing a rolling restart of an NDB Cluster with multiple management nodes, the management server reads its own configuration file if (and only if) it is the only management server running in this NDB Cluster. See Section 21.5.5, “Performing a Rolling Restart of an NDB Cluster”, for more information.

当管理服务器启动时，它首先检查同一ndb集群中的任何其他管理服务器，并且在成功连接到其他管理服务器时使用其配置数据。这意味着除非管理服务器是唯一运行的服务器，否则将忽略管理服务器重新加载和初始启动选项。这还意味着，当对具有多个管理节点的ndb集群执行滚动重新启动时，如果（并且仅当）管理服务器是此ndb集群中运行的唯一管理服务器，则管理服务器将读取其自己的配置文件。有关更多信息，请参阅第21.5.5节“执行ndb集群的滚动重启”。

Python 2.6 or higher.  The Auto-Installer requires the Python interpreter and standard libraries. If these are not already installed on the system, you may be able to add them using the system's package manager. Otherwise, they can be downloaded from http://python.org/download/.

Python2.6或更高版本。自动安装程序需要python解释器和标准库。如果系统上尚未安装这些程序，则可以使用系统的包管理器添加它们。否则，可以从http://python.org/download/下载它们。

Paramiko 1.7.7.1 or higher.  This is required to communicate with remote hosts using SSH. You can download it from http://www.lag.net/paramiko/. Paramiko may also be available from your system's package manager.

paramiko 1.7.7.1或更高版本。这是使用ssh与远程主机通信所必需的。您可以从http://www.lag.net/paramiko/下载。paramiko也可以从系统的包管理器获得。

Pycrypto version 1.9 or higher.  This cryptography module is required by Paramiko. If it is not available using your system's package manage, you can download it from https://www.dlitz.net/software/pycrypto/.

PyCrypto 1.9或更高版本。paramiko需要此加密模块。如果无法使用系统的包管理，可以从https://www.dlitz.net/software/pycrypto/下载。

SSH.  A secure shell connection is used to enable the back end to perform actions on remote hosts. For this reason, an SSH server must be running on the remote host. In addition, the operating system user running the installer must have access to the remote server, either with a user name and password, or by using public and private keys.

宋承宪。安全外壳连接用于使后端能够在远程主机上执行操作。因此，ssh服务器必须在远程主机上运行。此外，运行安装程序的操作系统用户必须具有访问远程服务器的权限，可以使用用户名和密码，也可以使用公钥和私钥。

HTTPS.  Remote communication between the Web browser front end and the back end is not encrypted by default, which means that information such as the user's SSH password is transmitted as cleartext that is readable to anyone. For communication from a remote client to be encrypted, the back end must have a certificate, and the front end must communicate with the back end using HTTPS rather than HTTP. Enabling HTTPS is accomplished most easily through issuing a self-signed certificate. Once the certificate is issued, you must make sure that it is used. You can do this by starting ndb_setup.py from the command line with the --use-https and --cert-file options.

https。默认情况下，web浏览器前端和后端之间的远程通信不加密，这意味着用户的ssh密码等信息以明文形式传输，任何人都可以读取。要加密来自远程客户端的通信，后端必须有证书，前端必须使用https而不是http与后端通信。启用https最容易通过颁发自签名证书来实现。颁发证书后，必须确保使用了该证书。可以通过使用--use https和--cert文件选项从命令行启动ndb_setup.py来完成此操作。

Certificate-based authentication.  The back end ndb_setup.py process can execute commands on the local host as well as remote hosts. This means that anyone connecting to the back end can take charge of how commands are executed. To reject unwanted connections to the back end, a certificate may be required for authentication of the client. In this case, a certificate must be issued by the user, installed in the browser, and made available to the back end for authentication purposes. You can enact this requirement (together with or in place of password or key authentication) by starting ndb_setup.py with the --ca-certs-file option.

基于证书的身份验证。后端ndb_setup.py进程可以在本地主机和远程主机上执行命令。这意味着任何连接到后端的人都可以负责命令的执行方式。若要拒绝到后端的不需要的连接，可能需要证书来验证客户端。在这种情况下，证书必须由用户颁发，安装在浏览器中，并提供给后端用于身份验证。您可以通过使用--ca certs file选项启动ndb_setup.py来制定此要求（与密码或密钥身份验证一起或代替密码或密钥身份验证）。

Welcome: Begin using the Auto-Installer by choosing either to configure a new NDB Cluster, or to continue configuring an existing one.

欢迎：开始使用自动安装程序，要么选择配置新的NDB集群，要么继续配置现有的NDB集群。

Define Cluster: Set basic information about the cluster as a whole, such as name, hosts, and load type. Here you can also set the SSH authentication type for accessing remote hosts, if needed.

define cluster：设置集群整体的基本信息，如名称、主机和负载类型。如果需要，您还可以在这里设置用于访问远程主机的ssh身份验证类型。

Define Hosts: Identify the hosts where you intend to run NDB Cluster processes.

define hosts：标识要在其中运行ndb集群进程的主机。

Define Processes: Assign one or more processes of a given type or types to each cluster host.

定义进程：为每个群集主机分配一个或多个给定类型的进程。

Define Attributes: Set configuration attributes for processes or types of processes.

定义属性：为进程或进程类型设置配置属性。

Deploy Cluster: Deploy the cluster with the configuration set previously; start and stop the deployed cluster.

部署集群：使用之前设置的配置部署集群；启动和停止部署的集群。

Python 2.6 or higher.  The Auto-Installer requires the Python interpreter and standard libraries. If these are not already installed on the system, you may be able to add them using the system's package manager. Otherwise, you can download them from http://python.org/download/.

Python2.6或更高版本。自动安装程序需要python解释器和标准库。如果系统上尚未安装这些程序，则可以使用系统的包管理器添加它们。否则，您可以从http://python.org/download/下载它们。

Paramiko 2 or higher.  This is required to communicate with remote hosts using SSH. You can download it from http://www.lag.net/paramiko/. Paramiko may also be available from your system's package manager.

帕拉米科2或更高。这是使用ssh与远程主机通信所必需的。您可以从http://www.lag.net/paramiko/下载。paramiko也可以从系统的包管理器获得。

Pycrypto version 2.6 or higher.  This cryptography module is required by Paramiko, and can be iunstalled using pip install cryptography. If pip is not installed, and the module is not available using your system's package manage, you can download it from https://www.dlitz.net/software/pycrypto/.

PyCrypto 2.6或更高版本。paramiko需要此加密模块，可以使用pip install cryptography安装。如果未安装PIP，并且使用系统的包管理无法使用该模块，则可以从https://www.dlitz.net/software/pycrypto/下载该模块。

SSH.  A secure shell connection is used to enable the back end to perform actions on remote hosts. For this reason, an SSH server must be running on the remote host. In addition, the operating system user running the installer must have access to the remote server, either with a user name and password, or by using public and private keys.

宋承宪。安全外壳连接用于使后端能够在远程主机上执行操作。因此，ssh服务器必须在远程主机上运行。此外，运行安装程序的操作系统用户必须具有访问远程服务器的权限，可以使用用户名和密码，也可以使用公钥和私钥。

HTTPS.  Remote communication between the Web browser front end and the back end is not encrypted by default, which means that information such as the user's SSH password is transmitted as cleartext that is readable to anyone. For communication from a remote client to be encrypted, the back end must have a certificate, and the front end must communicate with the back end using HTTPS rather than HTTP. Enabling HTTPS is accomplished most easily through issuing a self-signed certificate. Once the certificate is issued, you must make sure that it is used. You can do this by starting ndb_setup.py from the command line with the --use-https (-S) and --cert-file (-c) options.

https。默认情况下，web浏览器前端和后端之间的远程通信不加密，这意味着用户的ssh密码等信息以明文形式传输，任何人都可以读取。要加密来自远程客户端的通信，后端必须有证书，前端必须使用https而不是http与后端通信。启用https最容易通过颁发自签名证书来实现。颁发证书后，必须确保使用了该证书。通过使用--use https（-s）和--cert file（-c）选项从命令行启动ndb_setup.py可以完成此操作。

A sample certificate file cfg.pem is included and is used by default. This file is located in the mcc directory under the installation share directory; on Linux, the full path to the file is normally /usr/share/mysql/mcc/cfg.pem. On Windows systems, this is usually C:\Program Files\MySQL\MySQL Server 5.7\share\mcc\cfg.pem. Letting the default be used means that, for testing purposes, you can simply start the installer with the -S option to use an HTTPS connection between the browser and the back end.

包含一个示例证书文件cfg.pem，默认情况下使用该文件。该文件位于安装共享目录下的mcc目录中；在linux上，该文件的完整路径通常为/usr/share/mysql/mcc/cfg.pem。在Windows系统上，通常是C:\ Program Files\MySQL\MySQL Server 5.7\share\mcc\cfg.pem。允许使用默认值意味着，出于测试目的，您可以使用-s选项启动安装程序，以便在浏览器和后端之间使用https连接。

The Auto-Installer saves the configuration file for a given cluster mycluster01 as mycluster01.mcc in the home directory of the user invoking the ndb_setup.py executable. This file is encrypted with a passphrase supplied by the user (using Fernet); because HTTP transmits the passphrase in the clear, it is strongly recommended that you always use an HTTPS connection to access the Auto-Installer on a remote host.

自动安装程序将给定集群mycluster01的配置文件保存为mycluster01.mcc，保存在调用ndb_setup.py可执行文件的用户的主目录中。此文件使用用户提供的密码短语（使用fernet）进行加密；由于http在clear中传输密码短语，强烈建议您始终使用https连接访问远程主机上的自动安装程序。

Certificate-based authentication.  The back end ndb_setup.py process can execute commands on the local host as well as remote hosts. This means that anyone connecting to the back end can take charge of how commands are executed. To reject unwanted connections to the back end, a certificate may be required for authentication of the client. In this case, a certificate must be issued by the user, installed in the browser, and made available to the back end for authentication purposes. You can enact this requirement (together with or in place of password or key authentication) by starting ndb_setup.py with the --ca-certs-file (-a) option.

基于证书的身份验证。后端ndb_setup.py进程可以在本地主机和远程主机上执行命令。这意味着任何连接到后端的人都可以负责命令的执行方式。若要拒绝到后端的不需要的连接，可能需要证书来验证客户端。在这种情况下，证书必须由用户颁发，安装在浏览器中，并提供给后端用于身份验证。您可以通过使用--ca certs file（-a）选项启动ndb_setup.py来制定此要求（连同或代替密码或密钥身份验证）。

Welcome: Begin using the Auto-Installer by choosing either to configure a new NDB Cluster, or to continue configuring an existing one.

欢迎：开始使用自动安装程序，要么选择配置新的NDB集群，要么继续配置现有的NDB集群。

Define Cluster: Set basic information about the cluster as a whole, such as name, hosts, and load type. Here you can also set the SSH authentication type for accessing remote hosts, if needed.

define cluster：设置集群整体的基本信息，如名称、主机和负载类型。如果需要，您还可以在这里设置用于访问远程主机的ssh身份验证类型。

Define Hosts: Identify the hosts where you intend to run NDB Cluster processes.

define hosts：标识要在其中运行ndb集群进程的主机。

Define Processes: Assign one or more processes of a given type or types to each cluster host.

定义进程：为每个群集主机分配一个或多个给定类型的进程。

Define Parameters: Set configuration attributes for processes or types of processes.

定义参数：为进程或进程类型设置配置属性。

Deploy Configuration: Deploy the cluster with the configuration set previously; start and stop the deployed cluster.

部署配置：使用先前设置的配置部署集群；启动和停止部署的集群。

Automatically save configuration as cookies: Save your configuration information—such as host names, process data, and parameter values—as a cookie in the browser. When this option is chosen, all information except any SSH password is saved. This means that you can quit and restart the browser, and continue working on the same configuration from where you left off at the end of the previous session. This option is enabled by default.

自动将配置保存为cookies：将配置信息（如主机名、进程数据和参数值）保存为浏览器中的cookie。选择此选项时，将保存除任何ssh密码之外的所有信息。这意味着您可以退出并重新启动浏览器，然后从上次会话结束时关闭的位置继续使用相同的配置。默认情况下，此选项处于启用状态。

The SSH password is never saved; if you use one, you must supply it at the beginning of each new session.

ssh密码永远不会被保存；如果您使用一个密码，则必须在每个新会话开始时提供它。

Show advanced configuration options: Shows by default advanced configuration parameters where available.

显示高级配置选项：默认情况下显示可用的高级配置参数。

Once set, the advanced parameters continue to be used in the configuration file until they are explicitly changed or reset. This is regardless of whether the advanced parameters are currently visible in the installer; in other words, disabling the menu item does not reset the values of any of these parameters.

设置后，高级参数将继续在配置文件中使用，直到它们被显式更改或重置。这与高级参数当前是否在安装程序中可见无关；换句话说，禁用菜单项不会重置任何这些参数的值。

You can also toggle the display of advanced parameters for individual processes on the Define Parameters screen.

还可以在“定义参数”屏幕上切换各个进程的高级参数显示。

This option is disabled by default.

默认情况下禁用此选项。

Automatically get resource information for new hosts: Query new hosts automatically for hardware resource information to pre-populate a number of configuration options and values. In this case, the suggested values are not mandatory, but they are used unless explicitly changed using the appropriate editing options in the installer.

自动获取新主机的资源信息：自动查询新主机以获取硬件资源信息，以预填充许多配置选项和值。在这种情况下，建议的值不是必需的，但除非使用安装程序中的相应编辑选项显式更改，否则将使用这些值。

This option is enabled by default.

默认情况下，此选项处于启用状态。

Contents: Show the built-in user guide. This is opened in a separate browser window, so that it can be used simultaneously with the installer without interrupting workflow.

内容：显示内置的用户指南。这是在一个单独的浏览器窗口中打开的，因此可以在不中断工作流的情况下与安装程序同时使用。

Current page: Open the built-in user guide to the section describing the page currently displayed in the installer.

当前页：打开内置的用户指南，找到描述安装程序中当前显示的页的部分。

About: open a dialog displaying the installer name and the version number of the NDB Cluster distribution with which it was supplied.

关于：打开一个对话框，显示安装程序名称和提供它的ndb群集发行版的版本号。

For distributions using yum or dnf, you can use the MySQL Yum Repository for NDB Cluster. See Installing MySQL NDB Cluster Using the Yum Repository, for instructions and additional information.

对于使用yum或dnf的发行版，可以使用mysql yum repository for ndb cluster。有关说明和其他信息，请参阅使用yum存储库安装mysql ndb集群。

For SLES, you can use the MySQL SLES Repository for NDB Cluster. See Installing MySQL NDB Cluster Using the SLES Repository, for instructions and additional information.

对于sles，可以使用mysql sles repository for ndb cluster。有关说明和其他信息，请参阅使用sles存储库安装mysql ndb集群。

Management node: management-server

管理节点：管理服务器

Data node: data-node

数据节点：数据节点

SQL node: server and common

sql节点：server和common

The server RPM (for example, MySQL-Cluster-server-gpl-7.5.3-1.sles11.i386.rpm), which supplies the core files needed to run a MySQL Server with NDBCLUSTER storage engine support (that is, as an NDB Cluster SQL node) as well as all NDB Cluster executables, including the management node, data node, and ndb_mgm client binaries. This RPM is always required for installing NDB Cluster.

服务器RPM（例如mysql-cluster-server-gpl-7.5.3-1.sles11.i386.rpm），它为运行MySQL服务器所需的核心文件提供了NdbCluster存储引擎支持（即作为一个NDB群集SQL节点）以及所有的NDB群集可执行文件，包括管理节点、数据节点和ndb-mgm客户端二进制文件。安装ndb群集始终需要此转速。

If you do not have your own client application capable of administering a MySQL server, you should also obtain and install the client RPM (for example, MySQL-Cluster-client-gpl-7.5.3-1.sles11.i386.rpm), which supplies the mysql client

如果您没有能够管理mysql服务器的客户机应用程序，那么还应该获取并安装客户机rpm（例如mysql-cluster-client-gpl-7.5.3-1.sles11.i386.rpm），它提供mysql客户机

Building NDB Cluster requires using the NDB Cluster sources. These are available from the NDB Cluster downloads page at https://dev.mysql.com/downloads/cluster/. The archived source file should have a name similar to mysql-cluster-gpl-7.5.16.tar.gz. You can also obtain NDB Cluster sources from GitHub at https://github.com/mysql/mysql-server/tree/cluster-7.5 (NDB 7.5) and https://github.com/mysql/mysql-server/tree/cluster-7.6 (NDB 7.6). Building NDB Cluster 7.5 or 7.6 from standard MySQL Server 5.7 sources is not supported.

构建ndb集群需要使用ndb集群源。这些可从位于https://dev.mysql.com/downloads/cluster/的ndb cluster下载页面获得。存档的源文件的名称应该类似于mysql-cluster-gpl-7.5.16.tar.gz。您还可以从github获取ndb集群源，网址为https://github.com/mysql/mysql server/tree/cluster-7.5（ndb 7.5）和https://github.com/mysql/mysql server/tree/cluster-7.6（ndb 7.6）。不支持从标准MySQL Server 5.7源构建NDB群集7.5或7.6。

You must configure the build using the WITH_NDBCLUSTER_STORAGE_ENGINE or WITH_NDBCLUSTER option in addition to any other build options you wish to use with CMake. (WITH_NDBCLUSTER is supported as an alias for WITH_NDBCLUSTER_STORAGE_ENGINE, and works in exactly the same way.)

除了要与cmake一起使用的任何其他生成选项外，还必须使用with-ndbcluster存储引擎或with-ndbcluster选项配置生成。（with ndbcluster支持作为with ndbcluster存储引擎的别名，工作方式完全相同。）